As the title says, you are unable to build on top of previous player built structures, even if they exist within your tribe, and even if they are your own. Even if you were to try say, assign a use to a building, it will show the message "You are not in this tribe!", which I think is related to being unable to build on top of old structures. The only way I've seen to fix this is to dismantle all pieces entirely and put them back together again, which will put them under your ownership, which still affects your own buildings that you previously built.

As far as I can see, the way to recreate this is to create a tribe, build something like trusses, floors, or a building that can be assigned a use. Then remove that tribe totem from the tribe, and replace a new one within. You shouldn't be able to use any of those structures anymore for building on top of, or assigning use, even if you own it.