I have seen dogs with ED before and never have I seen any kind of swelling at the joint. If anything, the only symptom has been lameness. Sometimes not even that.

What about a young male (6 months) that has significant swelling at both elbows, along with lameness? The swelling is like a hygroma on both elbows.

Has anyone seen ED present in this way?

Pet owners vet is diagnosing ED but no xrays have been done yet

absolutely some can pocket fill

Yes, absolutely.

Without at least a radiograph, there can be no assumption made of ED. That's an assumed,totally ridiculous diagnosis without x-rays and blood work.

I had a chocolate girl whose elbows swelled and she became upper quadrant, bilaterally lame at 18 months. She had full blow lyme disease with both IGG and IGM's both sky-high. Simple bloodwork and a radiograph should be the first order of testing.

The pet owner's vet sounds like an ass. As the breeder, you should ask for their permission to call him or her. That's what I would do if I were you.

Well anything other than ED/OCD in the elbows is a long shot but slightly possible.
Personally on cases like this (if it was one of our puppies) we have referred them to a specialist of our choice for a second opinion and paid the bill. If it was someone else's puppy, we still helped with the referral. I would not automatically assume the vet has no clue.