I have one user that is unable to place Protection stones. I cannot find a logical reason for this person to be excluded.

The user is in the same group as everyone else (GroupManager)
Everyone else in the clan can place them (SimpleClans)
They aren't getting any errors or warnings
it's not conflicting with anyone else's fields
I can place a stone myself and make them the owner and it works just fine after that
They are not sneaking when the block is placed
The console is not throwing any errors

I have used PreciousStones on my server for 3+ years and I am stumped. What else can I do?

Very odd, can't think of a reason.