[2020] Bosses in raids don't take aggro correctly.

For at least a month now bosses will randomly walk away from their tank in raids and then come back to them as if they've lost aggro, often in times where there isn't even anybody in the direction they are walking towards as everybody is stacked up - such as fights like Mursat Overseer.
I don't mind waiting for small bugs to be fixed over time but this can make a pretty big difference to a group, bosses like VG can walk into the wrong section and spawn an unaccessable green or simply losing large amounts of DPS because a boss moves out of where it is supposed to be stood. I can't ascertain the reason as to why the boss loses aggro but in our controlled group our tank had 1000 more toughness than the next closest guy and it still happens.
Edit 1: crappy formatting.