JIRA issue description doesn't save when using Firefox

When you insert a JIRA issue into a Confluence page the JIRA issue description is not always saved.

We noticed that this was only happening for some of our employees but not others. The employees all have the same permissions so It wasn't until we did some browser testing that we found the problem.

The JIRA issue description gets saved when Confluence is open in a Chrome browser but not when open in Firefox.