I have a Jira service project in PROD (v8.20.10), where Confluence (v8.5.4) is linked to the project to suggest articles.
When the keywords 'PIPS', 'Program', and 'Code' from the issue summary match with the Confluence article title (or the content), the related articles are suggested in the issue.

I have the same service project in UAT (v9.12.1) which is configured the exact same way, but the related KB articles do not get suggested.

If I remove 'PN 044438' from the issue summary, the articles are suggested.
Now, I have to upgrade Jira to v9.12.1 soon and this will be a problem as most of the issues will not show any related KB articles.
Is this a version problem? and is there another way to show the related KB articles without changing the issue summary?