Fork transaction failed

I’m getting this error on itself.

I have a group account and a user account which is a co-owner of the group. We have a private repo in the group account and I’m trying to fork it to my user account.

I am consistently getting a “Fork transaction failed.” error.

Is this a bug on or is it not possible to fork private repositories?

I am able to fork a random public project under my user account.

Thanks in advance.