Update the YouTube app: Make sure you have the latest version of the YouTube app installed on your device. Outdated apps can sometimes cause compatibility issues, including with Flex mode.
Restart your device: Sometimes, a simple restart can help resolve technical glitches. Try restarting your device and then launching the YouTube app again to see if Flex mode is working.
Check for Flex mode compatibility: Flex mode is a feature that is only supported on certain devices, such as Samsung smartphones with foldable screens. Make sure your device is compatible with Flex mode by checking the device specifications and requirements on YouTube's official website.
Disable and re-enable Flex mode: If you have Flex mode enabled, try disabling it and then re-enabling it again. To do this, go to the YouTube app settings, look for the Flex mode option, and toggle it off and on. This can help reset the feature and resolve any issues.
Clear cache and data: Clearing the cache and data of the YouTube app can sometimes help resolve issues. Go to your device's app settings, find the YouTube app, and then tap on "Storage." From there, you can clear the cache and data of the app. Note that clearing data will also sign you out of your YouTube account, so make sure to remember your login credentials.
Reinstall the YouTube app: If none of the above steps work, you can try uninstalling and reinstalling the YouTube app. This can help ensure that you have a fresh installation of the app without any corrupt files that might be causing the issue.
If you've tried all of these steps and are still experiencing issues with YouTube Flex mode, you may want to contact YouTube support or seek assistance from other YouTube users or forums for further troubleshooting.
The only way that worked for me was going to youtube via my phone's settings and uninstall all YouTube updates then turning off auto-updates. It goes back to factory settings which I was okay with since I use flex mode so much on YouTube and this bug (if it's a bug) frustrated me a bit too much haha