Group guest access via access request - Error


When a user requests access to a group with internal visibility and the administrator goes to review the request and grant the user access, the admin is unable to grant the user guest access to the group.
Error: Something went wrong on our end.
I must first add the user as developer, and can then change the user role to guest.

I can add the same user directly as guest to group if I do not use the access request.

Is this expected, and why?