Unable to add new member to Developer Hub

Hello,

For about 4 days, I have been trying to add a new member to our developer hub for them to assist with keycodes and release channel access. This person made a meta account and a meta developer account, but they do not possess a headset. 

I made sure they were logged into their account. When I enter in their email or username, it is unable to locate them. I confirmed that the spelling was correct and escalated this to my developer relations coordinator. If you have any resources on a fix for this, I would appreciate it. 

Thank you!