I have this same issue. No clock, no Control Center icon, no icons for the standard control center items like network and bluetooth. All menus blacked out in dark mode. Notifications coming through, but so fast they cannot be read.
Using the activity monitor, I found Control Center is running. But it is not displaying.
Given this the issue seems to have to do with Control Center's interface with the menu bar. Or rather the issue is with the menubar and not limited to Control Center.