Your story reminds me of my story with my DS7.
His big block was getting his face wet, which pretty much shut the idea of swimming down.
We did group lessons. We did individual lessons. We tried different instructors.
After a few weeks, this one instructor told me "I'm going to ask him to jump into the water. He'll probably get mad afterwards."
He jumped. He declared "THAT. WAS. AWESOME!!!" And thus began actual swimming. Six months later I still get giddy about him splashing around in the water with his friends.
I don't know when or how that will happen for you. Maybe it's not with this instructor or during this session. But just keep bringing him to the water and giving him the right to choose when he takes that big leap.
