Anyone else ever have this issue?

So I'm new to playing Shadow of War and I was/am trying to do my first online vendetta mission and I was tasked with opening 3 caragore cages, and outta like the 10+ they marked only one had a caragore? So now I'm stuck and cant progress the mission because I've opened all the cages and only got 1/3. So is this like a common bug and something I'm just gonna have to expect occasionally? Could it also be because I had previously attacked the fort/outpost the mission is in and in that time had already opened a lot of the cages and killed the caragores?