As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PDIS 691 21-31 2381531 20FEB21 PHL CLOSE AT 24K FEET. CABIN PRESSURIZATION IN AUTO MODE STARTED TO RAPIDLY RISE. FACT 20FEB21 21:48 PHL R & R GROUND CONNECTION VALVE IAW AMM 21-22-04 NEEDS OPS CHECK. PERFORMED PRESSURIZATION, OPS CK FOR GROUND CONNECTION VALVE IAW 21-31-00 OPS CK GOOD OK FOR SERVICE AT THIS TIME.