The additional logs didn't really clear anything up, for me at least. Perhaps we are just misinterpreting the message and it is really just a full cache that is the root of your problems.
But why are you moving your appdata from cache to the array? Most people want it to remain on cache, but if you want it on the array despite the performance hit your dockers would take, then why not simply create it on the array to begin with? Either cache-prefer or cache-only, or if you really don't want it to stay on cache, then cache-no, would make more sense than cache-yes for appdata. And mover probably can't move open files, so if you have your dockers running when mover is trying to move appdata then things aren't going to work anyway.
If you don't want to start over with your Backup share, then maybe you could stop your dockers until you get your cache straightened out, then start over with your dockers. And cache-prefer is probably what you should want for appdata and the other system shares. Your cache is probably large enough for typical use, you just overfilled it for this initial use.