Yep, that's the other way to solve moodle strange issues ... give it what it's looking for. :\
Think there are temp tables created for backups as well as restores. Most of the time ... actually never ... one doesn't see them. Some flag got set somewhere.
Now that you've restored a course .... does that course use/have that question type in a quiz y'all no longer use? Not sure how one finds a question type in the entire quiz bank but think to make your backups valid from this point forward you might have to find those and remove them from the question bank.
'spirit of sharing', Ken