Summary

Add-on which was working without any issues for a while suddenly stopped loading. The issue happens all the time and only for a few specific users, it works.

Environment

Jira Cloud

Diagnosis

HAR logs show no error however only a few "0"s which usually show up when request times out or there is no response.
When support tried to load the same app in the customer's env, it loaded without any issues as well.

Cause

The issue happened due to an internet security tool installed on machines that were blocking the content from add-on servers. 

Solution

Whitelist the add-on URL (which can be verified through HAR logs) in network settings or internet security tool settings, so that content is not blocked.