We got our Rocket.Chat server up and running and everyone but one person is able to use the android app. They have created a profile and it’s been approved but when they press the sign in button, nothing happens.
They’re using the latest version from the play store; 4.7.2.2126. on an LG Stylo 5. Android 9, security patch 1 March 2020, Kernel version 4.9.112
Server is running 2.4.9. Linux 4.15.0-76-generic
Fixed it. If anyone has this problem in future, go to Settings > General > Apps & notifications > App info > Rocket chat > storage> “clear cache” and/or “clear data”
Arr nope, this does not work
Sadly this does not work for me either 
Another user had the same problem and the app started working when running it in a sandbox.
Another user said their solution was to clear app data, un-approve and re-approve permissions, then reset the phone.