It’s possible that you added content into a compendium module rather than the world itself. In that case, you’ll want to check out the second section of that document which explains how to export your compendium modules from Forge Backing Up Your Forge Content
The world contains scenes (which contains tiles), actors, items, etc. You might not see all of the changes if you’re running a different set of modules or different versions of modules, or if they’re installed but not activated in the manage modules interface.