When I was asking you and @andybob for GPU usage screenshots 9 days ago it was for exactly the same thing as you, except for the poly-sinc filter for my i7-7700HQ (non 2s, non xtr). After you disable CUDA offloading, do a full system reboot. That got things back working for me. I went through the exact same last week. GPU usage was 0% (per our messages) but poly-sinc was working. Then going to the latest GeForce drivers made GPU active (yay) but made things worse (nay)