Are you still getting the issue? The SQLite locking up can be due to the size of your database files, or the amount of users that you have accessing the Ombi container at the same time. It really isn’t too bad getting the MariaDB/MySQL container up and running.
After reading through this forum, and poking around in the instructions, I finally figured out how to get the MySQL database to function and have my old database migrated over. I ended up using GIT on MacOS’ terminal screen and manually copying the python migration scripts over into the Ombi AppData folder.