Well, it seems clear that the issue is not with JRemote at all. It's with MC's connection to the DLNA renderer (the Linn device).
I'm guessing something changed in the recent update that makes DLNA connections different. I sorta remember some big change in DLNA late in the MC22 tree that triggered a number of complaints, but I can't remember any specifics.
You could try rolling back to an earlier version of MC22 to test and see if you see correct behavior then.
There are complex troubleshooting procedures that you could try also. The normal advice is to use the White Bear DLNA analyzer and then post its log file here. The author generally reads the logs and tries to help out.
White Bear and it's author are not associated with JRiver; he's just an enthusiast trying to help out. You can find the software with a search.
Good luck.
Brian.