Start Sprint date picker dialog does not work

Summary:

When starting a new sprint, attempting to use the date picker does not display the calendar pop up and the dates cannot be changed.

Steps to Reproduce:

1. Create a new board.
2. Add an issue to the sprint in the backlog.
3. Start the sprint.
4. Attempt to change the date.

Expected Results:

The calendar appears and the date can be selected.

Actual Results:

The calendar does not appear and dates cannot be entered.

Regression:

Untested in earlier versions.

Notes:

This was tested and works in 5.10.6. It may have been fixed in 5.10.5.2, however was not tested in that version.