Start Sprint fails with 24 hour time format

I like your way to improve planning activity (and not only planning) with Rapid Boards.

There is one bug.
In our Jira dates are displayed in 24-hours format.
When I click "Start Sprint" Jira asks me to input dates. Then in popup dialog dates are displayed in 12-hours format. After picking a date result string (with date/time) is incorrect. See an attached screenshot for details.