This wasn't in group finder but should be good enough(?).
I was fooling around with trash mobs outside of Firestar H4 entrance in Balmorra without Mako while waiting someone to invite me to their group. I get to group with two Marauders and Vette(?). Needless to say we didn't get that far without healer. I suggested that we use Mako instead of Vette and try again. Mako... Nope! Annoying ship droid it is (let me guess, without any gear?). We didn't have any problems vs. first champ. But here comes the weirdest part: one of the Marauders leave the group and we get thrown out of that instance. Other Marauder runs back in and I decided to follow him. I get Mako to help us and switch her to dps mode. What happened next was something I didn't expect: he is leaving too? No communication attempts from them at any point.
What I did wrong here? As a tank I'm supposed to keep all stronger mobs from bashing dps and help with trash as well if I can, right? I did that so what on earth I did wrong?
Funny thing about this was the fact that one of them was looking for tank and healer 30+ minutes later in General chat.