Restart the Telegram app (close and reopen).
Go back to Settings > Privacy and Security > Contacts.
Toggle "Sync Contacts" ON again.
Wait a few minutes for the re-sync to complete.
Clear Telegram Cache: Corrupted cache data can sometimes cause sync issues.
Open Telegram.
Go to Settings > Data and Storage > Storage Usage.
Tap "Clear Telegram Cache" (or similar option depending on OS). Confirm the action.
Restart the app.
Update Telegram App: Ensure you're running the latest version of Telegram. Bugs in older versions can sometimes cause sync problems.
Go to your device's app store (Google Play Store for Android, App Store for iOS).
Search for "Telegram."
If an "Update" button is available, tap it.
Manually Sync Contacts (Android Specific - Device telegram number database Settings): Some Android devices have a system-level sync option for accounts.
Navigate to "Accounts" (or "Accounts & sync," "Users & accounts").
Find and tap on your Telegram account (it might be listed under a Google or other account).
Tap "Account sync" and ensure "Contacts" is toggled on. You might also find a "Sync now" or "Sync" option (often under a three-dot menu).
Check Phone's Native Contact App:
Ensure the contacts you expect to see in Telegram are actually saved correctly in your phone's native address book (with proper names and international phone number formats).
If you manage contacts via a cloud service (e.g., Google Contacts), ensure that service is syncing correctly with your phone.