I think that the guys at JRiver have had some time off the latest days. That might be why you have gotten so slow response. Yes, I've gotten the impression that bugs like this is a priority.
I do not have much experience here, and I can't see any obvious things in the logs. Have you tried to run RO Standard, just to figure out if there are some HQ components messing up things? I think it would help very much if you could try to change certain things like different Video and Audio settings, so we could narrow it down a bit.