Sorry to hear that! I just got a PulsarOne as well and it paired instantly with my LeMond Dutch on the first try and has worked flawlessly. My only complaint is that there is a noticeable lag - maybe 1-2 seconds - between changing the assist level on the PulsarOne and when the new assist level actually kicks in on the bike. The lag with the PulsarOne is somewhat longer than when doing so using the button on the bike itself. But I now have a sense of the lag, so it’s becoming second nature to adjust the assist 1-2 seconds before I want the adjustment to actually happen. Still annoying, though.
Anyway: in doing some research before buying it, I do recall reading something somewhere - can’t remember if it was in the Pulsar One instruction manual, an online review, etc. - saying that the PulsarOne only works properly with motors having specific firmware versions. Perhaps the pairing problem is related to that? (If i can remember where I found the info about which firmware versions are needed in order for the PulsarOne to be compatible, I’ll post it. You might be able to find it faster through some googling.)