Yippee!

[Dogtrousers]

Simple fix
1) Long press the app icon.
2) Click the info icon on the top right corner to open the app settings.
3) Scroll down to storage row, and open it.
4) Clear cache and clear data.
5) Reopen the app and it should work as usual.

You are a hero.

You'd be even more of a hero if I hadn't just spent ages farting around getting it to work on the browser on my phone.