Lol, guess I’ll add my wild story to this one 
The first time I tried to engage, I had this same problem. Destroyed the two giants, noticed no lasers happened. She didn’t engage. I logged off/in, and she had reset.
So, I started the fight again. However, this time, the statues were doubled. That is, there were actually 2 standing on the same spot! So as soon as I engaged one side, I had to fight both giants, plus lasers.
I defeated the two from one side, and thought that I probably had to do the other side too. I started that fight…but because I’d killed two, the queen engaged too! So now it was 3 on 1! Well, thankfully the queen takes damage from the statues, so as they’d do their big sword attack, sometimes it’d hit her.
After a little bit, I noticed that the lasers started up again. So, 3 on 1, with lasers. Whee. Now if I’m recalling the order of events correctly, first the queen died. Her body disappeared immediately, and I was still in combat with the two statues. She immediately reappeared on her pedestal, and I believe the lasers stopped. I defeated one of the giants, and she jumped down and engaged again.
I killed her, and this time the body stayed around, and I think when she died the last giant stopped/died. I was finally able to loot and leave. But boy, defeating 5 giants and 2 queens was quite the workout 