Date Picker/Date Time Picker not working in sub-task create screen

Summary

When attempting to create a sub-task, if there is a field set as required, or a validator (e.g. field required validator) , the sub-task create screen will show up.

The date time/date time picker calendar icon does not work.

Environment

Jira Cloud

Steps to Reproduce

1. Make sure there is a field required for the Sub-task issue type;
2. Try to create a subtask.

Expected Results

The date picker is displayed and a date can be selected by clicking on the calendar icon.

Actual Results

The date picker is not displayed. The following error is displayed in the browsers development console.

Workaround

Enter the date manually using the default jira.date.picker.java.format: dd/MMM/yy - i.e. 30/Jul/19