Plugin (index.jelly) references to static files (javascript and css) are relative, changing them to absolute paths by prefixing them with resURL is a recommended practice - https://wiki.jenkins-ci.org/display/JENKINS/Basic+guide+to+Jelly+usage+in+Jenkins. The following commit may address this issue if it was caused by a failure to resolve paths.
Plugin (index.jelly) references to static files (javascript and css) are relative, changing them to absolute paths by prefixing them with {{resURL}} is a recommended practice - [https://wiki.jenkins-ci.org/display/JENKINS/Basic+guide+to+Jelly+usage+in+Jenkins.] The following commit may address this issue if it was caused by a failure to resolve paths. Need to confirm