Date Picker when setting the release date of an unreleased Version shows undefined for Japanese , Korean & Russian language

Summary

Users are unable to choose a date from the Date Picker when choosing to release an unreleased Version while using Japanese or Korean as its default language.

Environment

• Jira 7.3.6
• Jira 7.4.0
• Jira 7.5.0
• Jira 8.0.1
• Default Jira language is either Japanese or Korean

Steps to Reproduce

1. Set Jira default to Japanese or Korean
2. Go to a Software project and click on the Releases tab
3. Select the meatball menu (. . .) on an unreleased version
4. Click on Release
5. Click on the Calendar icon

Expected Results

A Date Picker that shows a calendar by month

Actual Results

The Date Picker will only show a single row with the words 'undefined' repeated again and again. Can be seen with the attached screenshots datepicker_japanese.png and datepicker_korean.png.

Screenshot of Jira in Japanese

Screenshot of Jira in Korean

Workaround

There is a feature to manage versions in the Project settings (under Project setting -> Versions). The Date Picker when releasing an unreleased Version under that tab works fine.