As others have reported, on both my iMac and MacBook running OS 10.15.1, after updating my Profiler to 7.1.7 and installing RM 3.0, RM will open and start synching, then crash and shut down. I've tried uninstalling and reinstalling multiple times on both computers. Same result. I even tried installing RM 3.0 on my VERY old MacBook running 10.13.6, samre result.
This must be some sort of Mac - USB - Kemper thing. Possibly unrelated, but whenever my Profiler is connected to my MacBook and the Macbook isn't connected to an external power supply, (i.e., running on battery only) my Profiler would freeze up and need re-booting (this with the official RM release before 3.0). This too was not unknown or unreported on this Forum. The suggestion was this was a Kemper- USB issue. Dunno.
While unable to run RM 3 at this point is frustrating, it is somewhat comforting knowing my problem is shared by a number of others. It's not just me!