Issue Collector shows a blank page when using custom issue collector form template

Summary

When using custom issue collector form template, it just presented with a blank white page and you can also see a blank screen in the Template Preview

Environment

• JIRA version 1000.362.1 Cloud

Steps to Reproduce

1. Add Issue Collector
2. Select custom for Issue Collector Form Template
3. Submit Issue Collector

Expected Results

Fields are displayed

Actual Results

Shows a blank page