I tried out CircleCI's Gitlab integration a few weeks ago during the public beta, and it felt like CircleCI was really phoning it in.
The instructions led me down paths where the product would just break. It told me to connect CircleCI to Gitlab through OAuth, and then my first build immediately died asking for a personal access token.[0] I generated a PAT instead, and then CircleCI failed my build because it was provisioning an empty SSH private key.[1]
They had a channel for reporting bugs with the integration, but it doesn't create a real support ticket. Their feedback channel was just their public Canny feature request board. I submitted my feedback anyway, and they didn't respond for over two weeks, at which point the response was basically just, "Oh, we fixed a lot of bugs, so maybe we fixed yours. Can you delete everything and try again?"
[0] https://twitter.com/deliberatecoder/status/15430630495982714...
[1] https://circleci.canny.io/gitlab-vcs-experience-feedback/p/n...