Wonder if anyone can help.

I'm having an odd issue with Vodoriga Sleepers where I can't spawn the last set required to open the door to Demon Wall.

I've tried literally everything I can think of. I've pulled all the mobs around it to get a clear run and no matter where I stand and what I do, they just will not spawn. In runs with my FC I need another member to pop them for me.

I've seen plenty of videos and other tanks seem to have no issue with this, and I've also looked everywhere and can't find anyone else experiencing this issue.

This surely can't be working as intended?