Most add-ons that are integrated into the issue details view won't load when you view an issue from the side panel. The behaviour is the same for all add-ons for any type of project in Jira.
- Install an addon on your Jira (in this example tempo timesheets was used)
- Go to your project's issues panel and select a random issue to view (if it doesn't happen on the first try select another random issue)
On the side view, the issue details will appear along with its fields and the add-on integrated amongst them.
The add-on will not load, it takes a few seconds to attempt to load and then fails with this message:
There is no actual workaround besides refreshing the page or clicking again on the issue, then the issue will reload with the add-ons loaded.