Was the update to your OS or the app? Either way, you might consider clearing the app cache for that app. You could also try reinstalling the app (which will likely require signing back in and you MAY need to ensure file associated with it are backed up but I don't have experience with the app).
Lastly, you may just need to contact the app developer -
support.android@musical.ly
If you need additional help or have more questions or details to share, please join the site so you can reply in this thread. See
this link for instructions on how to join Android Central.