LSX 629 impression off issue

2007 LSX 629 doesn't print on the last 2 sheets.
This only happens with certain types of trip offs. For instance, the mechanical double sheeter as well as the ultrasonic detector both trip normally and all of the sheets print. A lay light trip (either side or both sides) the press trips off normally and all sheets print. Using AMR reserve to sheet off, the press prints on all of the sheets normally. However, using the feeder pump off button or the production stop button, the last two sheets fail to print, come out blank, but are coated. This happens every time, consistently. The pump reacts normally to the button push, turning off instantly. No extra sheets feed into the stream. I've tried adjusting the sensitivity of the impression on sensor with no good results, still two blank sheets. This will happen on all stocks, cover as well as book. I'm not understanding the relationship of the pump off to impression control. Don't the lay lights control the impression off here?
Any thoughts would be appreciated.
Thanks

 

With this one you need to get Komori Electrician, something is tripping the printing units before they should go off.