Sprint date throws invalid format error when JIRA is in Korean

Steps to Reproduce

1. Switch JIRA default language to Korean
2. Create a new sprint in a blank project
3. Start the sprint with the start date and end date
4. Edit the dates by click a date from the pop-up calendar

Expected Results

Date are set correctly

Actual Results

Invalid date format error is shown

Notes

If the Start Date and End Date is not modified (using the suggested date), JIRA accepts the date format

Update

The problem occurs for custom date fields as well