I have a very similar issue with BESR 8.5, whereby recovery points are stated as unavailable. If I restart the service on the server it is moaning about, the status updates and it shows that the recovery point is available. I have a feeling it's something to do with the way the clients report to the manager. It might be reporting whilst mid-image-backup, though I'm not sure. I would definitely try and restart the BESR service on the client to refresh teh status.
Tbh, 8.5 seems to be quite buggy with a number of things, and still havent had any updates. I'm not sure if they are known issues, or indeed an issue with the software at all, but they are really annoying! I have recovery points which are created in the shared folder but the software shows no sign, and states the back up was last completed a day prior. The event log shows that the scheduled recovery point had started, but gives no more info. after that...not even a failure. It's pretty minor, but it would be nice to have a weeks worth of backups without any hiccups.