Let’s see that could happen.
Apparently on the update procedure the app settings was erased app “forgotten” the database location. In the usual scenario this should not to occur.
If the app does not see the database it starts initialization procedure of the new database. What you should to do is to locate the database on the your device and specify to it in the initialization screens by using the Advanced mode. (If you already to passed initialization procedure, you should to delete the new and empty database firstly, then restart the app.)
The second (but not the last) method is to restore the your last backup copy of the app’s database. (Are you have made it periodically, right?) To do it just create the empty database and restore your backup via options menu.