The Bookmarking feature doesn’t usually have any issues but experiencing issues with the Twitter app on your device can affect this feature. Firstly, check your internet connection. If your device is not connected to the internet or your connection is unstable, you’ll think that you’ve bookmarked a tweet without actually doing it. That’s why the tweet won’t appear in the “Bookmark” tab when you finally do have a connection. Secondly, check for updates. Older app versions can cause some features not to work. Go to the Google Play Store or App store to see if there are any updates. Another reason can be that your operating system is not up to date. This can also lead to apps not working correctly. Thirdly, you can try to restart your device. By restarting it, some temporary bugs can be fixed. You can also try uninstalling and reinstalling the app to “restart” it. This will require your login information. Fourthly, you can clean the cache memory of the app. Cache builds up over time and can result in some features not working. Clearing it out will give you a “restart” effect without losing any data or changing any settings. If you are experiencing these issues on a browser, try clearing out the browser cache.