I was thinking like jujunet that the number of leds for the addressable headers must be stored somewhere. No luck searching the registry but after expanding my search I found them! In the Lighting Service folder open the file LastProfile.xml and scroll to the bottom. Ta Da! That's the good news. I uninstalled Aura Sync and replaced it with the latest version of Armory Crate. All my devices are recognized and you can actually update the number of leds. Unfortunately it doesn't stick, completely. You still have to disconnect/reconnect the header to make it work but it persists if you only restart. If you shut down completely it breaks again. Also, check out the LightingService.log file and you'll see that the values seem to be coming from the xml file. It also seems to be calculating and/or writing the number here: AACAddressableStrip::DoMakeLeds. I'm getting close...
LightingService.log