As an admin, if you export the sc_cat_item list entries, there will be many more items in the export than you see in the list in the platform.
The business rule "Hide items for admin homepage" is removing items from the list.
If you wish to view all the items, you can disable the business rule.
1) Navigate to System Definition > Business Rules
2) Locate the BR named: Hide items for admin homepage
3) Open the record and uncheck the Active checkbox
4) Save the record