Epic Panel fails to load when board JQL has a large number of issues

Issue Summary

If a board has a large number of issues (over 10K in most cases), the Epic Panel in backlogs will fail to load and provide a generic error to contact support.

Steps to Reproduce

1. Create a board and use a JQL filter that returns more than 10K issues
2. Go to the backlog view
3. Epic Panel will fail to load, and an error message will appear.

Expected Results

Epic Panel should display results as usual.

Actual Results

Depending on if the enhanced board view is enabled, you'll see a 500 error or a generic error after ~30 seconds of the Epic panel loading.

Workaround

Currently, there is no known workaround for this behavior. A workaround will be added here when available.