FYI: Called the hospital on Phangan today, where I got my booster shot.
The reason it was not showing on Mor Prom app was because, as I got the two original shots on Koh Tao, and then the booster on Phangan, they assigned a different 13 digit ID number.
After calling and giving the vaccine dept. my original ID number, they had it added to Mor Prom in an hour ????