Good news! Worklogs - Time Tracking and Reports team has 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!
Improvements:
The “Week Start Day” setting from Worklogs Configuration page now applies to calendars in the Log Time Modal and the Add Holidays setting.
Bug fixes:
Fixed a bug that caused the “Number of days” field to reset to 1 in the Worklogs Gadget edit mode.
Fixed a bug that visually reset the “Select Default Time Range” option in on the Worklogs Configuration page.
Fixed a bug that caused a display of error flag when the licence expiration is was near (less than 5 days). Now the correct info flag is displayed.