Just wanted to add, that I had this similar issue happen for our monthly backup jobs recently. And for one of our servers, the F:\ drive (strange....same drive letter as your instance :) ) did not show up as restore selections.
Unfortunately, I was not able to look through any event logs and see why this occurred (as we did a migration for that server not too long ago) But, in the job log, that drive was indeed being backed up.
The only way I was able to have the selection reappear was to re-catalog the selected tapes for that job.
So, now I have to go back to the other month that happened and re-catalog the tapes for it as well.
Very strange why it happened. So, I also will be paying more attention to the full backups, especially since I have a monthly backup next week!
Good luck to you.
Brian