Read this on the Thaiger about Thai Pass:

The system still does not accept Microsoft email addresses like the popular Hotmail domain, and those who submit with an email address from there will not receive confirmation. Microsoft is said to be working on resolving the problem now.

The Foreign Ministry offered the following suggestions for possible reasons the people are not receiving their QR code after submitting all their information at the Thailand Pass website:

Your email address is incorrect or the account’s storage is full

You have entered the same information or attempted to apply for the Thailand Pass several times

You did not upload a clear and valid Covid-19 vaccination passport

The documents that you submitted do not meet the requirements, like a hotel that doesn’t have RT-PCR testing available, etc.