Same thing happened to me. Someone overlapped a claim flag on my land and around 3 blocks ended up belonging to them that was attached to my base. Took a while for me to notice and sadly they will not remove them.
I found this blueprint, but I have no idea where the skill to craft one comes from? Does anyone know? Also how do you craft using a blueprint like this wooden bow, I have everything, but I cant craft it.
Logged off for the night and when I came back someone, somehow took one of my claims that overlapped another and because of this, I can no longer build anything.