Error: Invalid Email during recharter

Our Committee Chair is trying to recharter and getting the following error.

Error Invalid Email: xxxxx@gmail.com
Whoops! It looks like we were unable to generate your charter for signature.

The email address in question is valid and looks OK in the members profile.

We tried this with different logins and with different browsers (Firefox, Chrome, Edge) - all with the sane result.

Any ideas on what can be done?