As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CRUISE FLIGHT AUTOPILOT B DISENGAGED AND FIRST OFFICER LOST FLIGHT DIRECTOR. RIGHT SIDE HDG BUG ALSO FROZE AND WOULD NOT MOVE. APPROX 30MIN LATER THE RIGHT SIDE FLIGHT DIRECTOR REAPPEARED AND A/P B WAS REENGAGED WITH NO FURTHER ISSUE. GROUNDED - YES. REMOVED & REPLACED MCP REF B737-800 AMM 22-11-34-400-801. OP CK'S AND ALL LLM TESTS CHECK GOOD PER THE SAME. GROUND VERIFICATION SUCCESSFUL.