updateGitlabCommitStatus doesn't work

I use "Only allow merge requests to be merged if the pipeline succeeds" configuration for MR in gitlab and updateGitlabCommitStatus in the pipeline Jenkinsfile.

It used to work, but now may (be to an upgrade of Gitlab or Jenkins) it doesn't work anymore.

I have two installation and both have the same issue.

### Production
git-client Version: 2.7.6 (pinned to fix previous bug)
git Version: 3.9.3 (pinned to fix previous bug)
gitlab-plugin Version: 1.5.11
Jenkins ver. 2.164.1
GitLab ver. 11.9.6

### Test
git-client Version: 3.0.0-rc
git Version: 4.0.0-rc
gitlab-plugin Version: 1.5.11
Jenkins ver. 2.164.2
GitLab ver. 11.9.7

I checked the jobs logs and server logs but I didn't find any clue related to this.