I agree. In such a situation, I propose to display a note in the "Nodes" section: all nodes are in exclusive mode.
And "label-less" jobs will be listed in the Orphaned Jobs section.

See attached screenshot.

Herbert, do you have any additional feedback?

Code changed in jenkins
User: Dominique
Path:
src/main/java/jenkins/plugins/linkedjobs/actions/LabelDashboardAction.java
src/main/java/jenkins/plugins/linkedjobs/settings/GlobalSettings.java
src/main/resources/jenkins/plugins/linkedjobs/actions/LabelDashboardAction/index.jelly
src/main/resources/jenkins/plugins/linkedjobs/settings/GlobalSettings/config.jelly
http://jenkins-ci.org/commit/label-linked-jobs-plugin/9b99377455e7e8e70e969bc3fe8fe7128ca2061d
Log:
JENKINS-25163JENKINS-25188 Take into account jobs with no labels

Hi Dominique, looks great! I do not have additional comments/feedback.

Included in release 3.0.3 of plugin. It should be available in the plugin admin section in Jenkins in the next few hours.

Herbert, out of curiosity, how many nodes and how many jobs do you have on the instance of jenkins where you use the plugin?

Hi Dominique,

We have 3 nodes (each 1 executor) and about 80+ jobs. The jobs were mostly tied to a specific node (this is how my predecessor set it up) since the nodes run integration tests using a database and the local jms server.

I was trying to see if I could better use these 3 nodes, so insight was step 1. Your plugin is a great source to get an overview and to predict what will happen when you change labels and node set up.

The last few weeks I have been tweaking with the settings of the nodes, and since I did not think well and your plugin did not mentioned orphaned jobs I set all node to Label restrictions. Along came the ever waiting jobs .

Thanks for your feedback.
If you're happy of the new feature in release 3.0.3 can you flagged this issue as resolved and close it? Same for Jenkins-25163. Thanks!