I know some services don't like privacy-focused email addresses, especially temp mail accounts. I have problems with my Proton or Tuta account sometimes, so that could be the reason, though if you spam the reset button and the email eventually gets sent out, there's a chance it's a problem with their mailing provider. CMIIW.

Btw, if OP wants to update this thread regularly, I suggest improving the presentation of such updates. For example, attaching an image instead of a simple paragraph would make the post more interesting for most users.