As you can see, I have a loot bag on, which I was not aware of until after my pet had stolen a MoN. The loot bag does NOT show up in any of the three tabs of the pet equip/unequip view. That said, it seems that maybe the issue is that even when I click buttons for second and third, it still only shows first pet? When I click the other pets on my bishop, it very obviously changes. But it's always looked like that on Tentomon, so I am a bit confused. Please fix asap.
This isn't a bug with pets, it's a bug with the chat bar. In general it seems to eat clicks if it overlaps some other UIs, which is what's happening here - clicking to pet 2/3 isn't working because it eats that click. I believe this also happens with some store stuff, but not 100% sure where else, I just remember it's a thing I've seen before.
Ohhhh, so it is! I did not even notice. That is some really shoddy programming. I'm guessing that this is never going to be fixed, because these kinds of bugs tend to be due to fundamental design flaws in how events are handled. Shame on Nexon.