I’m sure it’s been mentioned, but maybe she could benefit from a sponsor peer? Our puppy was a swimming sponsor for 12 years. Dogs who were terrified of water would come to the pool with our dog and would usually be broken of the fear at least in shallow water within the first 30 minutes. After 3 swims they were almost always on their own after that without any issues. There was only one dog that never swam and that was of a possibly abusive owner.

So maybe there is a puppy friend that she is fond of that can make her feel at ease? Hope it helps, good luck!