Good news! Worklogs - Time Tracking and Reports team have just released a new version, and since you use Jira Server you can decide to upgrade at any time! All that is needed is a click of a button in the Apps management screen on your instance!
New features:
Option to display selected data as a bar chart. It is now possible to represent Categorized by as a pie chart in both Worklogs report and Gadget, with the ability to download the chart
Bugs:
When an invalid filter was used in the gadget it was not possible to re-configure it
In some rare cases, the total row was duplicated in the Worklogs table
Fixed problem with Default view not being saved when the page was refreshed
Some XSS could be passed through fields value