As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON FLIGHT 4015 (YOW - DTW) CREW REPORTED DIFF PRESSURE WARNING AND SOME PAX FELT DIZZY AND LIGHT-HEADED. CREW THEN MANUALLY DEPLOYED O2 MASK BUT SEATS 8A+B O2 MASK DID NOT DEPLOY. INSPECTED AND FOUND 8 AB PASSENGER O2 MASKS NOT PROPERLY PACKAGED CAUSING O2 COMPARTMENT DOOR TO JAM. VERIFIED DOOR LATCH MECHANISM WAS ACTIVATED AT TIME OF DEPLOYMENT. RESET LATCH AND REPACKED MASKS PER CRJ 200 AMM 35-21-09. OPS TEST GOOD OF DOOR LATCH AND PAX O2 SYSTEM PER AMM 35-20-00.