It's either blush or the brushing liquid that's bothering the varnish. I always wet sand my epoxy with soap and water before varnishing since the blush is water soluble. If it doesn't finally dry, you could try to remove the varnish with a scotch bright pad or steel wool and or maybe acitone as a solvent with it. don't use strippers since they attack epoxy. Then wet sand the entire surface with soap and water. Let it sit for a few days and do a trial patch with the varnish. If the varnish is thin it should be sandable in a day or two.

I once painted a chesapeake over blush. It never dried. Never. I had to remove it. I don't know chemically what happens. I do know that blush will keep oil based paints and varnish from drying no matter how hard you pray.