Thanks for reaching out.
It does appear that your website domain is correctly whitelisted, just as you mentioned and so Login With Amazon flow should ideally work fine.
I checked https://www.treeseeds.com/login but didn’t find ‘Login With Amazon’ button to try it out. Is there a place I can try out this flow on your website, for helping you better?
Can you provide additional details like screenshot of the error and the URL at the time of the error for us to debug further?
You can securely email this information to email@example.com, and we shall investigate further.
Login With Amazon