Big issue I'm just experiencing.

I have partially built watch towers. I cannot build the final upper floor. I get no prompt unless I am above the watch Tower. For example if I position a canopy tent next to the open side of the watch Tower and boost up with people, I can build it and get the prompt. Otherwise I can't. This is true for dozens of watch towers.

Basically you cannot build a floor unless your character somehow is at a higher elevation than the watch Tower. In practical terms it makes it impossible to build.

Needs fixing urgently.