As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UNABLE TO TRANSMIT OR RECEIVE HF1 AND HF2 WHILE AIRBORNE. HF TEST PRE DEPARTURE WAS OK. GROUNDED - YES. REMOVED & REPLACED TRANSCEIVER REF B737-800 AMM 23-11-21 OPS CHECK OF HF1 & 2 GOOD SEAMC ANDY NOTIFIED OPENED FVR LOG PAGE 60483767 C/N 06007513 ETOPS FLIGHT VERIFICATION REQUIRED CREW TO CHECK OPERATION OF HF1 & HF2 GROUND VERIFICATION SUCCESSFUL