I ran a Ms. Liberty TF on my Thugs/Time MM. Henchmen die; it happens. But when I was re-summoning them to refilll their ranks back up and I was in combat, the pets would not reappear in my detailed pet tray. Sometimes they would summon, and other times no new henchmen would repopulate and the power would just finish casting with no effect.
Another bug was that I could completely dismiss all pets, run into an elevator, and attempt to resummon all my pets and nothing again would appear. Then several seconds later, my older henchmen would come through the elevator.. AND be clickable by me to command/dismiss... but I had a completely empty pets control/status window. When I manually clicked on each actual pet and dismissed them via that pet's drop down, they would skedaddle. Then and only then, was I able to completely recast all my pets.