Mirroring Github repos doesn't synch, eventhough it claims it has

As the subject line says, the pull mirroring from Github does not work, despite the Gitlab UI claiming that it did a successful pull X minutes ago.

We’re using Gitlab on-premises Ultimate Licenser. We’re setting up pull mirroring from Github.com for a twenty-some repos. We have a CI/CD setup, but it’s not the non-triggering of the CI/CD that’s the problem. The problem is that the repos just don’t update at all (and the pulls are done to branches that are not setup for CI/CD anyway)

The funny part is that 1) Gitlab UI claims is has done successful pull X minutes ago (where X is somewhere between 0 and 30 minutes), but nothing has been synched, and 2) the synch has worked for 5 of these 20 repos, while 15 are failing (but claiming to succeed).

A click on the “synch” button starts the synch, and a “The Repository is being updated…” popup, but this popup doesn’t go away (I don’t know if it’s supposed to). And still nothing really synchs, though a refresh of the page claim a successful pull:

As a new user on the community forums, it seems I cannot post images. I tried to upload screen dumps of the “Mirrored Repositories” UI bit in Gitlab, where you can see the claim that a successful pull had been done 19 minutes ago, and then masked screen dumps of the Github and Gitlab repos respectively, showing the same repo, same branch, where the Github showed a push on december 10th, and the Gitlab repo still claiming that the most recent push was 5 months ago (and of course, a different push ID).

Of the 20 mirrored repos, 5 of them seems to have synched, maybe because of various experimenting with many presses on the synch button and experimenting with removing branches and re-instating them, but it’s getting messy, and I would actually like the pull to just work… especially since Gitlab claim they HAVE worked. If they don’t work, I’d like an error message as to why.

Best place to start - check all the log files under /var/log/gitlab the log files there should at least have some detail related to the syncs or lack of.