Boundary issue / Room scale

Hello unity devs,

I didn't find anything on this topic here in the dev forum. But this should also target other devs:

I can't get room scale to work atm with v74.0.2 of the meta all in one sdk.

As some other users / players noted the boundary changed (somehow in v74?). https://communityforums.atmeta.com/t5/Get-Help/Boundary-bug-I-ve-never-seen-before/m-p/1303816/highlight/true#M359878 
For me I had this teardrop "stationary" boundary in my app, which uses "room scale" and worked before. Whenever I step outside the boundary my content disappears and a popup asks me if I want to create a new boundary.

For an unknown reason the quests goes into "stationary" mode when I start my "room scale" app!

This guy mentions to go to the quick settings and turn on "free room" instead of the "stationary": https://communityforums.atmeta.com/t5/Get-Help/Quest-3-suddenly-won-t-save-use-roomscale-boundaries/m-p/1309377/highlight/true#M362193 

That works and now I have "free room". But "free room" is NOT "room scale" and this is not a solution! Because the "free room" boundary is not as big as my whole room and I can't move around in the full room.

What changed? How to get "room scale" back to working?

Thanks