Btw, I have the same problem. I think something is not quite right with the build...

The legacy GJ loading parameter was just removed. It used to force plugin loading when GJ was detected and GJs menu was enabled. This was misleading behavior as enable GJ enabled loading of all plugins and not just GJ. The defaults for "Plugin Menus" and "Compact" will be set to "Show" and "Yes" respectfully in a later release to ease the usage and prevent overflow problems. Will also review adding migration for the legacy GJ param.

forge.joomlapolis.com/issues/7278

Found the "problem". It sets the setting to in CB Admin module to "hide extensions" and "Compact" to no... Furthermore, the Hide is not cached (ie the admin plugin menus disappear) but the other way around, it is cached (the plugin menues do not reappear unless you clean browser cache).

There is no "hide extensions" functionality. The "Compact" mode compacts the plugins under a single parent menu item so your menus don't overflow the top bar. They'll all be under Community Builder > Plugin Management or just under Community Builder if you disabled CBs menu item output.