As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
03/02/2020 - PRELIMINARY SUBMISSION: LP1140723 ITEM 1 -- 5-10 MINUTES AFTER APU + PACK START UP CABIN FILLED WITH SMOKE/ FUME / SMELL . BURNING SMELL AND REDUCED VISIBILITY IN CABIN OBSERVED BY ALL 6 CREW MEMBERS . TURNED OFF APU BLEED +APU.