Hi Jon144~ If you prime the cartridge with the priming syringe and tilt it exit valve down, then tap the exit channel a few times, but ink does not enter the exit channel, then I suspect there may be a blockage in the exit channel (possible a small piece of plastic from the manufacturing process?), since you were able to easily prime another cartridge (they should be very easy to prime). Can you please attach a photo of the suspect cartridge so I can see the exit channel area, with the cartridge facing exit channel down, and also let me know what color position this cartridge is for. We will get this resolved for you.
Best regards~ Dana