As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BOTH TRANSPONDERS LOSE ALTITUDE INPUT FOR 1 MINUTE WHEN SWITCHING BETWEEN ADC 1 AND ADC 2. MFG TECH SUPPORT STATED THEY ENGINEERED A 1 MINUTE DELAY IN ALTITUDE REPORTING AFTER RECEIVING A VALID ALTITUDE AND INCORPORATED THE DELAY IN A SOFTWARE REVISION BEFORE THE 2.09 REVISION. THE MFG TECH DID NOT KNOW THE EXACT SOFTWARE REVISION IT WAS INCORPORATED ON.