That's definitely a serious problem, but I can't reproduce it on any of my devices, because when I switch between apps, MobileSheetsPro doesn't reload for me. The only way I can imagine forcing MoblieSheetsPro to reload when switching apps is to either set the background limit under Settings->Developer Settings->Background Process limit to "No Background processes" or enable Settings->Developer Settings->Don't Keep Activities under the tablet settings. You definitely wouldn't want either of those settings set that way though, as that would cause major problems with MobileSheetsPro. You didn't change any of those developer settings on your device, did you?
As a side note, for testing purposes, I set the background process limit to "No Background Processes", then edited a song in MS Pro, then switched apps, and then switched back. I then got the database loading message and it caused major problems with the app. I had to force kill it and reload it. My database was fine after the reload though, so I'm not sure why the database became 0 bytes for you. SQLite is supposed to prevent that kind of data loss, and the database shouldn't have been written to during initialization.
Mike
As a side note, for testing purposes, I set the background process limit to "No Background Processes", then edited a song in MS Pro, then switched apps, and then switched back. I then got the database loading message and it caused major problems with the app. I had to force kill it and reload it. My database was fine after the reload though, so I'm not sure why the database became 0 bytes for you. SQLite is supposed to prevent that kind of data loss, and the database shouldn't have been written to during initialization.
Mike