Start with Joomla cache cleared and a hard refresh on the front end. Most issues are module assignment, empty categories, or asset loading.
Confirm articles are published, categories or tags match the module filter, Count is not zero unintentionally, and Featured Articles setting includes the items you expect. Check menu assignment so the module runs on the page you are viewing.
Upgrade to 1.0.3 or newer. Builds before 1.0.3 used a custom separator field that did not load in the module form; section titles appeared as empty text inputs. Current releases use Joomla native note fields for Layout, Article settings, and Images settings.
Verify media/mod_rca_timeline exists after install. Clear cache. Try toggling Font awesome or Use jquery if icons or scripts conflict with the template.
For style9, set ordering to Created Date with Ascending direction. Other sort fields may not match the horizontal design assumptions.
Check image source toggles and Placeholder Path. Confirm GD is available if you use resize modes other than None. Thumbnail cache may write under images; ensure the folder is writable.
Confirm the installed ZIP is a retail RCA build whose manifest includes the public updateserver URL. Confirm the production feed and L2 ZIP on recreatinganew.com match the version you expect.