In Live edit, when you delete a floor that has structural integrity enabled, all props around it will also be deleted. This is cool for BR, but in Creative and Live edit we NEVER want that to happen. Imagine swapping a floor in a room because you don’t like its design, then everything around you gets deleted, potentially the entire building if you are not careful. And all this is by default in UEFN. Oh, and let’s not forget that placing architecture from UEFN then opening live edit will delete it if its in the air, again by default.
How to fix:
-Toggle setting in World Settings in UEFN: Spawn registered in structural grid ON/OFF, Spawn as forcibly structurally supported ON/OFF
-Toggle setting in Quick Build menu (inside Live edit): Destroy surroundings on floor destruction: ON/OFF
And the defaults should be OFF, OFF, OFF
Lastly as an extra, would be cool to have a visualization option that shows which pieces are structurally supported or not, because there is no indication atm and it can cause destructive issues in projects that use builds (remember if something is destroyed within live Edit, which always happens in this issue, there is no undo action).