macOS 27 beta has broken most menu bar management apps. Bartender, Barbee, Ice, Thaw, Sane Bar, Glow and also BTT's menubar management features all broke completely.
This is because Apple completely changed the menubar architecture (again). Previously the system reported every menu status item as a separate small window, which third party apps could interact with (in limited but useful ways). For example third party apps could capture the contents of these windows, move the windows around and hide them using some tricks. They could even access them while they were off-screen. Now all of the menu bar items are represented by only one window, so the whole architecture most of the menu bar manager apps were built on needs to change.
I have been digging into other ways to achieve menu bar management on macOS 27 Golden Gate and I while I initially thought Apple had blocked all viable ways, I think I now found two possible ways forward. I have tried implementing the first one in BTT 6.569 (All current and previous BetterTouchTool releases for download).
There is now an action "Load Menu Bar Layout", which allows you to specify the layout you want to load and apply it. You can assign it to any trigger in BTT, so e.g. you could create shortcuts to switch between the various layouts you create:
If this works well, I'll share my findings with the open source menu bar managers soon.
Note: both ways are not official, so Apple might block them at any time during the beta phase.