Things that have been eliminated as problem: battery, ignition switch, start stop switch, dfi relay, ignition coils, ignition pulse triggers, and
junction box. The variable here is the igniter. Although it seems to function once the bike is started and continues to until the ignition switch is turned off, I would not eliminate it until I was able to try another for testing. There are no test procedures for an igniter. Perhaps you can find one for a loaner. The part # you need is: 21175-0048. '05 ~ '08 Nomad. I would suggest if you have not already done so, disconnect and inspect all connector plugs, look for bent or damaged pins, use a dielectric grease and reconnect . Good luck, and keep us posted with results.
I couldn't sleep last night thinking about this damn thing. I was looking up the ignition system, and igniter was one I was reading about. It's built into the ECU....and I have been suspecting the ECU. I see a local Nomad for sale, would perhaps offer the guy some money for a few minutes of testing. I would think a VN1600 ECU of the same vintage would work as well?
I'm also looking to checking the crankshaft sensor. Not much else out there to check.