bugged interaction - Union of souls with map boss - Jade Isles

I don't know if this is intentional or not, but after you phase the boss past phase 1 he loses all of his union of souls stacks, which loses all the rarity and strength. on the minimap it shows 2 separate boss icons, one from phase 1 and 1 that you are fighting.

occurred to me today as well, phase 1 at 25 stacks, phase 2 and 3 at 0. was looking forward to a long boss fight :(