I have had something similar happen in FMGo 15. Intermittently. Completely bypassing security. We are talking days not minutes. The FMGo app usually freezes up for some reason. App needs to be swiped up to close it. On App restart it logs into the last opened file with the last used credentials. Sometimes it is not the last used file. Even scarier.
I have not had time to get enough information on this to report it properly, but it is an issue.