What a PITA. Could you try a 70/30 or even 80/20 poly/turps mix for a first coat? Obviously solvent is loosening the stain. But is it the turps, or is it something else that’s already in the poly to start with?

I’d suggest testing on some scrap wood to see if it’s the turps or the poly. Of course it may prove to be both with that particular stain pigment.