Same problem for me. I’ve followed the documentation extensively here: Unreal Engine 4 on GitHub - Unreal Engine
I’ve unlinked, and re-linked about 100 times, and I’ve also checked my spam folders.
Opened up a support ticket but was treated like a robot, and was told they couldn’t help, despite the documentation specifying to reach out to customer support in the specific event that you do not receive the GitHub org invite email.
If you don’t receive a confirmation email, or if your account is experiencing problems, get help from Customer Service.
Can somebody at Epic confirm whether or not this is a bug on your end? Or maybe just add us to the org manually in the meantime?
My GitHub username is razic.