I finally finished the base for my friends and I, we were so happy. But when I went to put down the claim flag it said the area was already claimed buy there was no structure, sign, flag, or anything in site. It said that this random spot that is open to everyone is already claimed...
Cam flag radii can not overlap. Your claim flag circle was too close to someone else's existing claim flag radius. ALWAYS place your claim flag before you build.
I know this now. At first I didnt see any bases but the bases was deep underwater and there was no way I could tell without diving...