New dark side Rey would attack forever.

Also had this problem in conquest. I used Rey (Dark side vision) consumable to go with SLKR, Kylo Unmasked, Malicos, and gear 8 Shin Hati and Marrok, up against Barris, Vader, Starkiller, Mara Jade and Visas at sector 1. I think Rey retaliated Starkiller at some point, and just kept hitting him for 3 minutes or so. I guess he healed more than the damage he received. When she stopped, I didn't have time to finish the battle.

If it matters, my data disks are: Guard and penetrate (green 3 dots), Entrenched (no glow, one dot) and Amplify agony (green, 2 dots).

We're tracking this issue on our end. 

Yeah nonstop attack and just heals more than damages