You still have to take the pre flight PCR and 1 when landing and on day 6-7 , if you test pos on pre flight 1 you won’t be allowed on the plane , if you test pos on either of the pcr’s on arrival you will be taken to a hospital or special ASQ HOTEL for 10 days at your own cost whether you have a cert or not
Mine never worked either even when putting in the info manually , never been asked for it , wouldn’t worry too much , seem like it doesn’t work for anyone Thai nationals included
if you land in Bangkok then it’s 7 days ASQ , if you fly to Phuket it’s 7 day sandbox and only confined to your hotel room until you get your neg result from the arrival PCR