When I view a confluence page that has JIRA issue references, if that page is in a space that is based on the default theme (new one), then the new JIRA Links is visible. However, for all spaces with the Documentation theme (which is 90% of our 50+ spaces), that feature is not visible.

Attached is what I expect to see within all pages - that is from Atlassian's documentation. But, you don't see that at all in Documentation theme spaces.