OK... I may have missed it but....
Where do you live.....
What is the elevation.....
What are the temperatures... It would make answering your questions more accurate if we knew a few things....
My thoughts.... Your smoker is cold... ambient temperature or colder... that is creating an "air dam" and stopping or blocking air flow... You need your smoker to be 5-10 degrees warmer than ambient so it acts as a chimney and sucks air through the MB mod and keeps the pellets lit....
I have had the same situation I think you have going... Start the
AMNPS... it burns for awhile then quits as the afternoon temps warm up, while the smoker stays cool.... the cooler air in the smoker gets heavier and will flow backwards, out the MB door holes... putting out the
AMNPS....
I had to turn on the smoker heat for a minute to warm it up... then turn it off...
I had the smoker operating great with the
AMNPS one day.... put a cold slab of pig belly in it.... the smoke started coming out the MB mod as the air in the smoke cooled from the pig belly...