Accepting Student Assignment

I have an enterprise account that allows me to have unlimited private repos for my students.

I posted an assignment link for my class. All students but 1 were able to accept the assignment and were added to my Student Team. The one student, after clicking on the assignment link was presented wtih a page with a disabled ‘Accept Assignment’ button. For some reason she is unable to accept from the page.

Has anyone bumped into this issue and have a solution to the problem?

I had a similar problem years ago.
The problem was the student used an old version of GitHub Classroom in previous years.
That time we solved by going to her GitHub settings, then Applications then Authorised OAuth Apps and revoking the permits and starting again the authorisation process.

Hopes it help