Muninn doesn't start anymore

When I select Muninn in the menu it doesn't show up. Also the menu is blocked until I press the back button. Anyone else with the problem?

I already restarted the watch, but that didn't help.

Also opening the settings in the android app doesn't work (probably because this tries to start the app on the watch first).

I didn't try to reinstall the app yet, because I fear all data will be lost. Or is it saved somehow?

PT2 (App 1.4.1.0 - OS v4.9.178)