On Manage Jenkins -> Configure System, in the Gitlab section, there's a Credentials section that had a drop-down list where I should be able to specify an API Token. The drop down says "-none" and has no other options. If I choose Add -> Jenkins, then under Kind I can select "GitLab API token" and put in the info, and click Add. But the credential I've added does not show up in the drop-down, so I can't select it, and I have the red "API Token for Gitlab access required" message.

I expect to be able to see the API token credential I have added in the drop-down list so I can select it and connect. But it is not there.

As a result I am unable to use the plugin at all.