I have same issue as in Re: Oracle Jet Charts Time Series Axis in apex 5.1.4 .
The issue has been fixed in apex 18.1(https://docs.oracle.com/database/apex-18.1/HTMRN/toc.htm#HTMRN-GUID-E7E2B2BF-C756-4241-89DF-8D6C60F9A12A )
Is there a way to fix it in apex 5.1.4. I used my local database to demonstrate the issue with the Packaged application "Sample Charts"
Chart when my System time zone +5.30
Chart : when change the Timezone
If you check in apex.oracle.com with sample chart application this is not an issue.