The run as administrator was a quick fix possibility.
I had some issues with my anitvirus software, Symantec's Norton 360, after the upgrade. It took several reboots and several days to get through all "We just blocked this" messages. Then when Norton finally let MC21 work, Windows Firewall popped up a couple of messages. Windows Firewall was supposed to be turned off by Norton 360, but in fact it was just being "managed" by Norton. So I told Windows Firewall to allow the activities it noticed, and have since turned it off as it should be. I still need to investigate what happened there.
Anyway, if the Merit system works, then it definitely sounds like some component is being blocked, or isn't registered.
I suggest configuring all your antivirus and firewall software to notify you with a popup when it does something, rather than automatically block some activity, and see if you can find what is stopping RO from working.
I'm using RO STD. Works fine on MC21.0.3.
EDIT: I see Yaobing is on the job. Hmmm. No internet means can't download a component. Could be the problem. I'll leave my comments above anyway.