Release app broken - how to debug

I’m trying to get an app onto the android play store. When running the app locally via

ionic cordova run android --prod --device

it works all fine.
However when building the app
ionic cordova build android --prod --release

and downloading it via internal test on the play store, the second time I open the app, I get a forever spinning splash screen.
When I kill the app and reopen, I get a white screen.

I’ve upgraded to the latest ionic pro version and since then it’s unusable, however that’s just a guess because I can clear the data on the device of the app and then reopen, so not sure what that means…
I’m not sure how to debug this issue, any suggestions? Is there a way to debug a release app?