diff --git a/backend/tenant_context.py b/backend/tenant_context.py
index aac56e0..5bb970a 100644
--- a/backend/tenant_context.py
+++ b/backend/tenant_context.py
@@ -80,7 +80,7 @@ def library_content_visibility_sql(
 class TenantContext:
     profile_id: int
     global_role: str
-    # Header > gespeichertes Profil > Fallback; Plattform-Admin ohne Header oft None
+    # Header > gespeichertes Profil > Fallback; Plattform-Admin ohne Header: Profil-Verein wenn existent
     effective_club_id: Optional[int]
     club_ids: frozenset[int]
     memberships: List[Dict[str, Any]]
@@ -100,7 +100,8 @@ def resolve_tenant_context(
     Mitgliedschaften: wenn nicht übergeben, wird aus der DB geladen (aktive Mitgliedschaften).
 
     Auflösung effective_club_id:
-    - Plattform-Admin: Header setzt beliebigen existierenden Verein; ohne Header → None.
+    - Plattform-Admin: Header setzt beliebigen existierenden Verein; ohne Header → gespeichertes
+      active_club_id falls der Verein existiert, sonst None.
     - Sonst: gültiger Header zwingend Mitgliedschaft — bei ``reject`` sonst 403, bei ``ignore`` wie ohne Header.
       Ohne gültigen Header: gespeichertes active_club_id wenn Mitglied; sonst einziger Verein;
       bei mehreren ohne gültige Vorgabe → min(club_ids) (Fallback).
@@ -118,6 +119,11 @@ def resolve_tenant_context(
             if not _club_exists(cur, header_cid):
                 raise HTTPException(status_code=400, detail="Verein nicht gefunden")
             effective = header_cid
+        elif (
+            stored_active_club_id is not None
+            and _club_exists(cur, stored_active_club_id)
+        ):
+            effective = stored_active_club_id
         else:
             effective = None
         return TenantContext(
diff --git a/backend/tests/test_access_layer.py b/backend/tests/test_access_layer.py
index 11654b3..ba8a628 100644
--- a/backend/tests/test_access_layer.py
+++ b/backend/tests/test_access_layer.py
@@ -2,7 +2,7 @@
 import pytest
 from fastapi import HTTPException
 
-from tenant_context import library_content_visibility_sql, parse_active_club_header
+from tenant_context import library_content_visibility_sql, parse_active_club_header, resolve_tenant_context
 
 
 def test_library_visibility_sql_platform_admin_no_filter():
@@ -74,3 +74,54 @@ def test_parse_active_club_header_non_positive():
     with pytest.raises(HTTPException) as exc:
         parse_active_club_header("0")
     assert exc.value.status_code == 400
+
+
+def test_resolve_platform_admin_uses_stored_club_without_header(monkeypatch):
+    """Ohne X-Active-Club-Id: effective wie gespeichertes Profil (Sync mit Dropdown/DB)."""
+    cur = object()
+
+    def fake_exists(c, cid):
+        return cid == 99
+
+    monkeypatch.setattr("tenant_context._club_exists", fake_exists)
+    ctx = resolve_tenant_context(
+        cur,
+        profile_id=1,
+        global_role="admin",
+        header_raw=None,
+        memberships=[{"id": 10}],
+        stored_active_club_id=99,
+    )
+    assert ctx.effective_club_id == 99
+
+
+def test_resolve_platform_admin_header_overrides_stored(monkeypatch):
+    cur = object()
+
+    def fake_exists(c, cid):
+        return cid in (5, 99)
+
+    monkeypatch.setattr("tenant_context._club_exists", fake_exists)
+    ctx = resolve_tenant_context(
+        cur,
+        profile_id=1,
+        global_role="superadmin",
+        header_raw="5",
+        memberships=[{"id": 10}],
+        stored_active_club_id=99,
+    )
+    assert ctx.effective_club_id == 5
+
+
+def test_resolve_platform_admin_no_header_stored_invalid(monkeypatch):
+    cur = object()
+    monkeypatch.setattr("tenant_context._club_exists", lambda c, cid: False)
+    ctx = resolve_tenant_context(
+        cur,
+        profile_id=1,
+        global_role="admin",
+        header_raw=None,
+        memberships=[{"id": 1}],
+        stored_active_club_id=123,
+    )
+    assert ctx.effective_club_id is None
diff --git a/backend/version.py b/backend/version.py
index 9b81e42..2b819a6 100644
--- a/backend/version.py
+++ b/backend/version.py
@@ -1,13 +1,13 @@
 # Shinkan Jinkendo Version Information
 
-APP_VERSION = "0.8.58"
+APP_VERSION = "0.8.59"
 BUILD_DATE = "2026-05-07"
 DB_SCHEMA_VERSION = "20260508049"
 
 MODULE_VERSIONS = {
     "auth": "1.2.1",  # Login-Rate-Limit 30/minute pro IP (vorher 5/minute)
     "profiles": "1.7.0",  # exercise_list_prefs JSONB (Standard Übungsfilter); Patch via ProfileUpdate + Json()
-    "tenant_context": "1.0.4",  # pytest: Unit test_access_layer.py + optional Integration test_access_layer_integration (PostgreSQL)
+    "tenant_context": "1.0.5",  # Plattform-Admin: effective_club ohne Header aus Profil active_club_id wenn Verein existiert
     "clubs": "0.4.1",  # Alle geschützten Endpoints Depends(get_tenant_context); profile_id/role aus TenantContext
     "club_memberships": "1.0.1",  # Depends(get_tenant_context)
     "club_join_requests": "1.0.1",  # Depends(get_tenant_context)
@@ -29,6 +29,14 @@ MODULE_VERSIONS = {
 }
 
 CHANGELOG = [
+    {
+        "version": "0.8.59",
+        "date": "2026-05-07",
+        "changes": [
+            "Aktiver Verein: Backend resolve_tenant_context für Plattform-Admin ohne X-Active-Club-Id nutzt gespeichertes active_club_id wenn der Verein existiert (kein effective=null nach hartem Reload mehr)",
+            "Frontend: Nach Vereinswechsel Profil neu laden; Dropdown-Wert aus effective_club_id / active_club_id / LocalStorage abgestimmt (getResolvedActiveClubIdForUi)",
+        ],
+    },
     {
         "version": "0.8.58",
         "date": "2026-05-07",
diff --git a/frontend/src/components/ActiveClubSwitcher.jsx b/frontend/src/components/ActiveClubSwitcher.jsx
index 0243b79..489eb24 100644
--- a/frontend/src/components/ActiveClubSwitcher.jsx
+++ b/frontend/src/components/ActiveClubSwitcher.jsx
@@ -1,4 +1,5 @@
 import { useAuth } from '../context/AuthContext'
+import { getResolvedActiveClubIdForUi } from '../utils/activeClub'
 
 /**
  * Zeigt einen Vereins-Umschalter, wenn der Nutzer mehreren Vereinen zugeordnet ist.
@@ -9,10 +10,7 @@ export default function ActiveClubSwitcher({ variant = 'sidebar' }) {
   const clubs = user?.clubs || []
   if (clubs.length <= 1) return null
 
-  const selectClubId =
-    user?.active_club_id != null && clubs.some((c) => c.id === user.active_club_id)
-      ? user.active_club_id
-      : clubs[0]?.id
+  const selectClubId = getResolvedActiveClubIdForUi(user)
 
   const isMobile = variant === 'mobile'
 
diff --git a/frontend/src/components/Navigation.jsx b/frontend/src/components/Navigation.jsx
index f56485f..e9c98de 100644
--- a/frontend/src/components/Navigation.jsx
+++ b/frontend/src/components/Navigation.jsx
@@ -1,5 +1,6 @@
 import { Link, useLocation, useNavigate } from 'react-router-dom'
 import { useAuth } from '../context/AuthContext'
+import { getResolvedActiveClubIdForUi } from '../utils/activeClub'
 
 function Navigation() {
   const location = useLocation()
@@ -7,10 +8,7 @@ function Navigation() {
   const { user, logout, setActiveClub } = useAuth()
 
   const clubs = user?.clubs || []
-  const selectClubId =
-    user?.active_club_id != null && clubs.some((c) => c.id === user.active_club_id)
-      ? user.active_club_id
-      : clubs[0]?.id
+  const selectClubId = getResolvedActiveClubIdForUi(user)
 
   const handleLogout = async () => {
     await logout()
diff --git a/frontend/src/context/AuthContext.jsx b/frontend/src/context/AuthContext.jsx
index 57b676b..5e06078 100644
--- a/frontend/src/context/AuthContext.jsx
+++ b/frontend/src/context/AuthContext.jsx
@@ -64,11 +64,25 @@ export function AuthProvider({ children }) {
     const uid = userRef.current?.id
     if (!Number.isFinite(cid) || cid < 1 || !uid) return
     localStorage.setItem(ACTIVE_CLUB_STORAGE_KEY, String(cid))
-    setUser((prev) => (prev?.id ? { ...prev, active_club_id: cid } : prev))
+    setUser((prev) =>
+      prev?.id
+        ? { ...prev, active_club_id: cid, effective_club_id: cid }
+        : prev
+    )
     try {
       await api.updateProfile(uid, { active_club_id: cid })
+      const profile = await api.getCurrentProfile()
+      syncStoredActiveClub(profile)
+      setUser(profile)
     } catch (e) {
       console.error(e)
+      try {
+        const profile = await api.getCurrentProfile()
+        syncStoredActiveClub(profile)
+        setUser(profile)
+      } catch {
+        /* ignore */
+      }
     }
   }, [])
 
diff --git a/frontend/src/utils/activeClub.js b/frontend/src/utils/activeClub.js
new file mode 100644
index 0000000..3c97671
--- /dev/null
+++ b/frontend/src/utils/activeClub.js
@@ -0,0 +1,32 @@
+import { ACTIVE_CLUB_STORAGE_KEY } from './api'
+
+/**
+ * Einheitliche Anzeige des aktiven Vereins: Abgleich mit effective_club_id, active_club_id,
+ * LocalStorage (Request-Header-Quelle), sonst erster Verein der Liste.
+ */
+export function getResolvedActiveClubIdForUi(user) {
+  const clubs = user?.clubs || []
+  if (!clubs.length) return null
+
+  const idInClubs = (id) =>
+    id != null &&
+    id !== '' &&
+    clubs.some((c) => Number(c.id) === Number(id))
+
+  const eff = user?.effective_club_id
+  if (idInClubs(eff)) return Number(eff)
+
+  const ac = user?.active_club_id
+  if (idInClubs(ac)) return Number(ac)
+
+  try {
+    const ls = localStorage.getItem(ACTIVE_CLUB_STORAGE_KEY)
+    if (ls && /^\d+$/.test(ls.trim()) && clubs.some((c) => String(c.id) === ls.trim())) {
+      return Number(ls.trim())
+    }
+  } catch {
+    /* ignore */
+  }
+
+  return Number(clubs[0].id)
+}