When using Slovak language, date is getting broken

Issue Summary

When the default language of the user is Slovak, the selecting date is adding a %p at the end

This is reproducible on Data Center: (yes) 

Steps to Reproduce

1. Go to Jira > select a company management project
2. Click project settings > Workflow
3. Add a screen to one of the transitions, and add a field date in that screen
4. Go to personal settings > Language Slovencina
5. Move the issue to the transition where you created the screen
6. Try to add a date

Expected Results

The date should contain AM or PM at the end

Actual Results

An %p is added at the end, instead of the AM or PM

Workaround

Changing the default language solves the problem.