I just had the same problem with a recent M4 lonex nozzle I ordered - in a gun with all lonex parts no less. Maybe it's a bad batch, but it could be the other internals (tappet plate, sector gear clip, etc).
The nozzle wasn't pulling back far enough to let a BB through, but did fire a bit like yours. My solution was to take a
fine file and very carefully sand off a tiny bit off the end of the nozzle. I had zero FPS loss afterwards doing this and the gun fires a consistent 405fps +/-1 and has no feeding issues anymore.
This is obviously a last resort kind of thing once you've eliminated other causes. You may also want to file down the front of the tappet plate a bit so it pushes the nozzle a bit further into the hopup when it fires the BB (doesn't affect how far the nozzle if pulled back). I usually do this to all my guns anyway
