I attempted to fork GNOME / GIMP · GitLab and failed because there was no SSH key configured on my gitlab account. I configured my SSH key, then used ssh -T git@ssh.gitlab.gnome.org to confirm it was working. The response said Welcome to GitLab, @sparr! which is good in that it indicates the SSH key is working for connection, but bad in that my gitlab username was, at the time, sparr0. I didn’t notice the discrepancy at the time, and I regret not stopping there, because I suspect it is connected to the root cause of the problem here. With the SSH key configured, I was able to create the fork fork https://gitlab.gnome.org/sparr0/gimp but attempting to git clone git@ssh.gitlab.gnome.org:sparr0/gimp produced ERROR: The project you were looking for could not be found or you don’t have permission to view it.. I got the same error trying to clone the main public repo git@ssh.gitlab.gnome.org:GNOME/gimp. Unfortunately, I then changed my gitlab username to sparr, which will make the username discrepancy difficult to troubleshoot. If necessary, I can change my username to some new arbitrary string to demonstrate that the discrepancy persists and perhaps make it easier to track down. I remain able to ssh -T, but still get the error when trying to clone my repo or the main repo. I queued my fork for deletion, which changed its name as visible above. I created a new fork and attempted to git clone git@ssh.gitlab.gnome.org:sparr/gimp.git and still get the same error.
I have asked about this in irc liberachat #gnome-hackers and matrix GNOME Infrastructure Team room.