As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
INTERMITTENT VTK FLAG ON FO SIDE ON 5 OCCASIONS. WITH SINGLE FMC OPERATION MESSAGE ON FO SIDE. ONE OCCASION OF DUAL VTK FLAGS ON BOTH SIDES. ON ALL OCCASIONS THE ISSUES FIXED THEMSELVES PRIOR TO COMPLETION OF CHECKLIST. GROUNDED - YES. PERFORMED B737-800 FIM 34-61 PAGE 36 MAP FLAG REMOVED MENU/IDENT DISPLAYED. OKAY TO SERVICE.