Collation shouldn’t really matter for this kind of thing, but personally I prefer all tables to be the same – Just to eliminate the slight chance of discrepencies.
If all schedules are intact, but the adverts won’t use them. Then there is likely something going on with the *_adrotate_linkmeta table. That’s how schedules are linked to adverts. Errors related to that should show up in the error_log.
If there aren’t any errors, simply re-saving the adverts with the schedules may just solve the issue.
You may want to match up all collations just to be sure. But since they’re all using utf8 in one form or another I don’t think it’s the issue. Doing some database maintenance, such as optimising and repairing tables may help more. You can do that from AdRotate > Settings > Maintenance, or via PHPMyAdmin.