diff --git a/apps/compliance-portal/src/components/TopBar/TopBarUserMenu.tsx b/apps/compliance-portal/src/components/TopBar/TopBarUserMenu.tsx
index cd4fe3428..c3daae9b0 100644
--- a/apps/compliance-portal/src/components/TopBar/TopBarUserMenu.tsx
+++ b/apps/compliance-portal/src/components/TopBar/TopBarUserMenu.tsx
@@ -58,7 +58,6 @@ const topBarUserMenuFragment = graphql`
   fragment TopBarUserMenu_identity on Identity {
     fullName
     email
-    locale
   }
 `;
 
@@ -136,7 +135,12 @@ export function TopBarUserMenu({ identityKey }: TopBarUserMenuProps) {
               }}
             >
               {URL_LOCALES.map(code => (
-                <DropdownRadioItem key={code} value={code} disabled={isChangingLocale}>
+                <DropdownRadioItem
+                  key={code}
+                  value={code}
+                  closeOnClick
+                  disabled={isChangingLocale}
+                >
                   {URL_LOCALE_LABELS[code]}
                 </DropdownRadioItem>
               ))}
diff --git a/apps/compliance-portal/src/lib/i18n/useChangeLocale.ts b/apps/compliance-portal/src/lib/i18n/useChangeLocale.ts
index a8d275dd9..156243091 100644
--- a/apps/compliance-portal/src/lib/i18n/useChangeLocale.ts
+++ b/apps/compliance-portal/src/lib/i18n/useChangeLocale.ts
@@ -44,11 +44,18 @@ export function useChangeLocale() {
     locale: UrlLocale,
     options: ChangeLocaleOptions = {},
   ) => {
+    // Persist and navigate without sequencing them: awaiting the mutation
+    // before navigation left a frame where Identity.locale already matched
+    // the new choice but the URL still had the old prefix, flashing the
+    // mismatch callout. updateLocale writes the store optimistically, and
+    // flushSync applies the URL change in the same paint.
     if (options.persist) {
-      await updateLocale(locale);
+      void updateLocale(locale);
     }
     if (locale !== currentLocale) {
-      void navigate(replaceLocaleInPathname(pathname, locale) + search);
+      void navigate(replaceLocaleInPathname(pathname, locale) + search, {
+        flushSync: true,
+      });
     }
   }, [currentLocale, navigate, pathname, search, updateLocale]);
 
diff --git a/apps/compliance-portal/src/lib/i18n/useUpdateLocale.ts b/apps/compliance-portal/src/lib/i18n/useUpdateLocale.ts
index 6856bbe06..560884cd8 100644
--- a/apps/compliance-portal/src/lib/i18n/useUpdateLocale.ts
+++ b/apps/compliance-portal/src/lib/i18n/useUpdateLocale.ts
@@ -53,6 +53,11 @@ export function useUpdateLocale() {
     await commit(
       {
         variables: { input: { locale } },
+        // Keep the Relay store in sync with the URL during locale switches so
+        // the mismatch callout never paints a one-frame desync.
+        optimisticUpdater: (store) => {
+          store.getRoot().getLinkedRecord("viewer")?.setValue(locale, "locale");
+        },
       },
       feedback,
     );