Pet Graphical Display Bug

Yesterday a full group of us Runners were running Elite Mariner's Reef. About half way through the run everyone's pets dissappeared but my own. Then, one of the group members said "Get your pets out guys". As if he was seeing the same thing.

Not sure what would've caused it, we dismissed and re-summoned and everything seemed normal again.

Running Watcher's Tomb and Kraken Mines during season 4, I remember rogues in particular would completely disappear from view on my screen and sometimes randomly pop back up (but not a way where the problem seemed to have resolve itself). Maybe the similar issue here with pets? Strange.