Claims to be unable to find backup, but can clean up versions
I have an ATIH 2019 incremental backup which I last added to in July 2020; but now, when I try to make another incremental version, it refuses to believe it has found it (the red x on the arrow from source to target). Nevertheless, clean up versions was able to remove some versions, so that part of the program seems to know that the backup it is looking at is the correct one, but the part that actually backs up evidently does not.
I have seen this kind of behavior before, ATIH (various versions) refusing to believe that a backup that it has made previously is indeed the correct one for a further backup, but not before thought to test it with clean up versions. Is there some way to overcome this problem without starting a new backup (??!!??).\