alpha, my KR808 passthru does that too. works for a few good vapes, then..nothing. I discovered that if I just reach down and unplug it from the usb port and plug it right back in, voila! works fine again! give that a try. weird, huh? almost like it has a cutoff/reset. It only quits working if I chain vape it, not if I wait a while between each inhale. maybe some of the electronically gifted will know what is going on.
oh, and sometimes if I blow a fast little puff INTO the mouthpiece before I inhale it will start up again. kinda like a reverse primer puff.