does anyone know how to fix media custom option being grayed out. when going to pdf

Why not save as to PDF., have you tried that?

Only reason I ever used print to PDF was in large scale/trade show graphics I got a nice really small PDF on large scale using that option. I could scale to fit media -- so the preview file got a lot smaller, and great to email and for server space on large quantity jobs.

When you want a PDF from an Adobe application like Illustrator, you will get the best quality with Save (as) PDF.

Don't use Print.