Hi KKlossen,
What version are you running. This problem was fixed round about build 1608
See https://forum.awareim.com/d/5616>
If memory serves - it was something to do with when a user saved a different layout for a query. I didn't catalog the thread with support but I know they logged in to my app to run some tests and discovered an issue which they fixed. but if you follow the suggestions in the post, you might get a useful error message that you can work with