The most common culprit is a weak connection. Check your signal bars — if you're on mobile data, switch to Wi-Fi or vice versa. Clear the app cache in your phone settings: go to Apps → TikTok → Storage → Clear Cache. If videos still freeze or buffer endlessly, the issue is usually bandwidth. Close other apps eating up traffic in the background.
A cluttered cache or an outdated version causes the interface to lock up. Update the app through the App Store or Google Play first. If that doesn't help, force-close TikTok and reopen it. On older devices, reducing video quality in settings (Profile → Settings → Data Saver) takes the load off significantly.
File size and format matter. TikTok accepts MP4 and MOV up to around 287 MB for longer content. If the upload bar stops moving, it's almost always a connection drop mid-transfer. Switch networks, trim the clip slightly, and retry. Drafts save locally, so you won't lose the video.
Check that notifications are enabled both in the app (Profile → Settings → Notifications) and in your phone's system settings. On iOS, Background App Refresh needs to be on. If the app was recently reinstalled, permissions sometimes reset silently.
This usually points to a server-side hiccup or a corrupted local index. Log out, clear cache, log back in. If specific hashtags or accounts simply don't appear, try searching from a browser — if results show there but not in the app, a full reinstall fixes it.