App Update stops button from working unless reinstalled

I updated an app on the store and a part of the app that wasn't part of the update stopped working. A button meant to navigate stopped working. But when reinstalled, works fine.
This issues still linger.
I have over 30,000 users already using the app.
What could cause the button to stop after an update yet works when a total reinstall is done.
App Update stops button from working unless reinstalled
 
 
Q