P10S is easily the worst designed fight in the history of FFXIV since ARR

[Naizakane]

It's a bad fight because it exploits the weaknesses of SE's servers in the pandaemonic bonds mechanics.

Whenever you have to locate another person to stack with or spread away from in tight spaces, as the game requires, its a total crapshoot. This game pings player locations unbelievably slowly, and when the game is restricting your positioning and pushing you around it can be hit or miss whether the game registers your movement or not.

This sounds a lot like a you problem.