I guess they added schizophrenia in the latest patch
here's to it getting fixed

This is a common bug that can be fixed by either you or the person you are trying to add to a lease reconnecting to the server. I am not sure how the issue works, or doesn't rather, but generally if I can't add someone to a lease I tell them to reconnect then also reconnect after. After I do that I can add them to the lease.