I tried the "AllowCORS" trick in Chrome but still couldn't get past the "Foreign National Header" error.
In MS Edge browser, I was getting to the end but repeatedly saw the API error there.
I then tried afresh in Edge, adding a space after my passport no, and...
This email came immediately:
I also added my pp number to my vax cert, so fingers crossed for a quick approval. I hope to fly on the 8th.