The reason why this happens:* Some customers are provided with some hotfix for an issue, until the actual fix is released in any future updates/releases. Since the overlay exists(/apps), the actual fix(/libs) won't even show up as working, until that overlay is removed.Moreover, the fixed file may have something more(e.g.: new feature/functionality or some optimization) than what exists in the overlay. Due to this, that new feature/functionality won't even work and thus, can result in other issu...

* Try running dispatcher flush manually from the instance on which the flush is configured.You can try running a curl command. The following docs may be helpful:https://experienceleague.adobe.com/docs/experience-manager-64/administering/operations/curl.html?lang=en#common-content-manipulation-aem-curl-commandshttps://experienceleague.adobe.com/docs/experience-manager-dispatcher/using/configuring/page-invalidate.html?lang=en#manually-invalidating-the-dispatcher-cache If it doesn't work, it means ...

You can refer to Content Fragment Core Component for reference.Sample:https://aemcomponents.dev/content/core-components-examples/library/page-authoring/content-fragment.html Github:https://github.com/adobe/aem-core-wcm-components CF Reference Docs:https://docs.adobe.com/content/help/en/experience-manager-65/developing/extending-aem/customizing-content-fragments.html#using-content-fragments-in-pageshttps://docs.adobe.com/content/help/en/experience-manager-core-components/using/components/content-...

* Which exact/complete versions of AEM 6.3 & 6.4 did you try this on? Were those the latest versions on both AEMs?* Can you also please share the exact steps in detail? You can also log a ticket with AEM Support team to get this issue resolved/attended to, at the earliest.