Unfortunately, upgrading to 13.0 made changes to your database. These changes prevent a successful conversion back to version 12.2. This is the likely reason your tickets are not importing properly. This was an important note of the initial 13.0 release notes. It is still at the top of the release notes.
- IMPORTANT: Due to the significant changes in SmarterTrack 13.x, you cannot downgrade or restore your installation to previous versions. (13.0.6514)
I suggest starting a chat with one of our customer service reps.