This is happening on two accounts. You summon the pack snail (haven't tried other illusions), and it's not visible, can't click it etc. The work around I found was to use /pet hide and see what the dialogue says. For me it returns one line saying pet hidden from view (pack snail) and 3 lines of pet is no longer hidden from view (deity pet, zelniak, familiar). You then hide the 3 visible pets again by right clicking - pet options - hide them all one by one. Then use /pet hide again and all 4 become visible, including the pack snail. You can now re-hide the unwanted pets again. I don't run around with a swarm of pets following me, and after I've given the snail a job to do, I unsummon him. But on trying to summon him again later on, sometimes he doesn't appear and I have to do the above.
