They won't fix it, it's been an issue for at least several years or more and they never sorted it when they were actually working on the game. Now it's on end of life support it will never happen. The issue is caused by doing too much damage right at the start before the first little servitor spawns. All you can do is hold the damage at the beginning and hope anyone else in the instance doesn't break it. Just use a primary or something until the mini servitors start spawning and don't super or heavy the boss right off the rip. You need to wait for all 3 of the mini servitors to die anyway if you want it heroic

This glitch has been happening since Beyond Light... I have a hard time believing they are ever going to fix it.