That all sounds very good Robert. The only thing I can see is maybe you are fermenting too long. I don't wait for a certain type of mold mat to form. I am just waiting enough fermentation and mold to form for the gel coats and placenta tissue to break down. For that to happen it generally takes about 3 days. I have found for myself in the past that fermenting too long diminishes the viability of seeds.
perhaps try a shorter ferment and see if that makes a difference.
I made a little pictorial on how to ferment and clean tomato seeds on my Northern Gardener page:
https://www.facebook.com/pg/Northern...44168162391039
clearly there are many other methods that work for people, this is how I do mine.
KarenO