In an effort to troubleshoot my now absent profile photo, I went to the Gravatar site and noted that the email address I used to register my Gravatar differs from the email address I use with this MPU forum. That said, the Gravatar site/service offers the ability to add an email address to my Gravatar account, however, that process is not working, as best as I can tell. I receive a confirmation email that I click to confirm with no positive or expected result, i.e. the email address I use here to be added to my Gravatar account.
I sent Gravatar support an email. However, they lack any sort of confirmation email to indicate that my support request was received successfully.