I would check the nozzle for wear, maybe just go ahead and replace it, and when you do, take the hotend out to see if the PTFE liner is trashed, as I talked about here: Hot End Clogs - The How & Why. Otherwise, it may just be that the filament is unrecoverable, which has been known to be the case on occasion. One way to check would be to use a new roll of a different brand of filament, preferably a known high quality one like Overture or Polymaker. If the new roll prints fine, then the old one is junk at this point. Something else to keep in mind: the RH reported by the dryer is the RH of the air at the sensor, not the moisture content of the filament, so it can never be 100% trusted, it is really just a reference.