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 bar chart in both Worklogs report and Gadget, with the ability to download the chart

Bugs: