hi friends!
i have just met the same problem while csanchez3 - https://developer.apple.com/forums/thread/655329?answerId=647946022#647946022's solution just help me out.
rvictl works for me in Big Sur 11.0.1 (20B29) with Xcode 12.2 (12B45b) after I loaded rpmuxd as described here. The path to rpmuxd's launchd plist may differ from the path in that article. I used this command to load it: sudo launchctl load -w /Library/Apple/System/Library/LaunchDaemons/com.apple.rpmuxd.plist