We've seen this issue for a while on various jenkins versions (even back in the 1.6 release stream)  and I'm only now getting around to reporting it (apologies for the delay).  When we use the copy artifact plugin and set a description, the description is not displayed on jobs when selecting "Build with parameters". 

NOTE: We do NOT run jenkins in our environment via docker, we install using the war file through chef, however the steps below are the quickest path to reproduce the issue.

 
Steps to reproduce:

1.) Download the latest docker image of jenkins:

 docker pull jenkinsci/jenkins:lts

2.) Start a clean instance of jenkins:

 docker run -p 8080:8080 -i -t jenkinsci/jenkins:lts

3.) Navigate to "http://localhost:8080" and Install the copy artifact plugin (others can be installed too but are not required to reproduce)
4.) Create a new job using "Build selector for copy artifact" populating the name and the description, then save the job
5.) When clicking "Build with Parameters" notice the description isn't displayed.

As far as I can tell, no errors are displayed in the jenkins log either.