Extended invulnerability on vivid harest boss pre phasing

Bug Report ID: #3.936.022.724

Regular Map instance harvest spawned double vivid harvest boss. Both bosses enter invulnerability at around 60% health, with one leaving it about 50 seconds into the fight for phasing, the other went on for at least another 2 minutes without being able to deal damage(the other boss died in the meantime and before it fell off)), in which the boss continued to attack me. After invulnerability fell off, fight continued normally. Notably the bosses were mostly performing the lurking lunge attack pattern for extended amount of time. Report send at the time of second boss phasing.