My content installed and shows in the Content Manager but not in the Smart Gallery, how can I get it to show in the Smart Gallery?

You can use the “Sync Local Content” in the Smart Gallery’s right-top menu.

Note: If you changed the folder or name, then the Sync Local Content will not recognize it.
If you still have an issue, then please contact Support.

Know more: https://forum.reallusion.com/436848/FAQ-Why-some-of-installed-packs-are-not-shown-on-the-Smart-Gallery