...I was recently given a lot of fabric from someones elderly Aunt that passed away. It had that old mildew smell to it. I can't tell you how many times I washed, soaked & sprayed those pieces of fabric (sometimes yardage) to get the smell out "just in case I might need it someday. I am still airing it and rewashing it, but refusing to throw it away. ...
Have you tried washing with borax, odoban or white vinegar yet? If you are not able to get the smell out, what will you do with those fabrics? Will you still keep them?