Seems to be a classic case of the engine being flooded. Raw fuel hitting the glow plug, and making it too cool to fire. It can be surprising how much is still in there after pouring it out of the muffler. Hence the spinning it without a glow plug in place to clear out the remaining excess. Afterwards, try starting without further priming first.
Just checked my NIB 46FX manual, and correct initial high speed needle is 1 1/2 to 2 turns out, so my previous comment was a little too rich. While not outrageously excessive, still could exacerbate the issue if the engine already has a bit too much fuel in it.
NiStarter meters can be notoriously off - mine is in the green even when nothing is attached! So check the glow on the plug just to verify. Not enough heat can lead to more cranking, which can lead to flooding.
While not as critical for initial starting, check your low speed needle. OS says with the carb fully closed, the needle should initially be exactly 1 turn out.