Gitlab it's not running any pipelines

I have an on premises installation of Gitlab which I keep fairly up-to-date. About two days ago I updated from 10.6.1 to 10.6.3. Afterwards no pipeline has been running. I need to restart gitlab in order to new pipelines get scheduled.

The .gitlab-ci.yml are OK according to CI Lint. Yet when I push to Gitlab no pipeline gets created. Where should I look for any clue?