Did you try different tactics during the first round, to see if that would have an effect? Try to get an archer close to where the dragon lands, to do as much damage as possible with Arrow Spray, a couple of Hail Attacks, Drain Willpower + CC, etc?
Maybe try having one of your characters delay their turn, so they end the first round.
You could try lowering the PS4 resolution, and see if that makes a difference.
If you have a save before finishing the fight with Leandra, you could reload and make a different choice with the soul forge.
If you perform the soul forge and take the sisters with you, Leandra will gain control in the final fight and switch sides; if you CC them or otherwise avoid killing them, Icara will take over again after a few rounds.
