I am at the second boss now, when I first tried him, I made it till he split in 2 and the sidewards shooter started.
now after dying and retrying, each time the boss is gone and only the sideways shootershoots.
but boss doesnt appear, despite the dialogue each time.
only some white blinking box every now and then at the top of the room.
so yeah, cant defeat the boss if he doesnt spawn again