yellow harvest boss endless spawning minions

Bug report reference number : 3,250,190,956

Currently in a t16 crimson temple, sacred grove, just got the t4 yellow harvest boss, got it to half HP it goes to its phase, but its just endlessly spawning minions and not ending, been 5mins of killing non stop, tried going in and out of portal but the minions dont stop spawning and boss never comes out of his phase

Edit for more context: So it looks like that I maybe killed the boss before it phased or it just despawned? but the phase still happened and because there was no boss the minions just kept spawning non stop.