No, it's not the database file or the data within it. For example the people having this problem can do a full good backup, delete the app, then re-download and restore the same database file and it seems to be working. You are the first who has said that this problem has come back.
If you are willing, we'd like to get you setup with a beta version that will have a more verbose error message that will hopefully help us track down what is causing this. We have not been able to replicate the issue here, but if you have then perhaps you can help us get this figured out. If you want to do this please write us at support @ on-core dot com.