My bench thralls that I have paid for or captured keep leaving the land claim area and go off the map. When I rescue them they will go in f9 by the lake and will be up in the air. 
Please copy this info and paste it into a new report. Thank you!
If you’re on a private server or single player, turn Living Settlements off. It’ll stop rogue thralls escaping your base.
Is that in the server settings on gportal?
Server settings