I switched back from the public test server this morning so I'm not sure if this was happening there too. I went to put an outpost down near AXL's arena in prep for the fight and was looking to see how close I could place a block. I was surprised to find that I could put a foundation down anywhere in the arena. I'm not sure if this is meant to be allowed or not, I can imagine most building would get destroyed or badly damaged in the fight.