When I target the blacksmith of mammon outside , I can target him but when you port inside he isn't there no matter how many times i typed. I thought maybe he disappeared but i could still target him with my spy outside !
Imo next time when it happend, get there some friends and ask him if he got same bug.
I did actually and they couldn't see him too, when he moved to DO i could see him again because you can see through the gate who is in or not. When i ported in Forbidden i couldn't even target myself or my bot when i was inside neither mammon.