I understand I should have used a different app for backing up my messages, but I did not. I used Titanium Backup and made a full backup of apps and data. I was apparently also using Android Messenger and not Google Hangouts to store my SMS. This service was apparently deprecated in August. I go to Titanium to restore my messages, and for a moment, it looks good! I see all my messages. Then they rapidly delete themselves before my very eyes!
I try again, I reload app + data, or data only, and the same thing happens---I see all my messages, then I watch it delete them one by one very quickly.
What is happening in this process, and how can I prevent it? Where are they going?
About adb backups, not Titanium Backup, is this Reddit thread relevant (could I get my SMS back if I have an old ADB lying around?)?