Adding a File Rule to the inventory File Scan only captures count and size information for the specified File Type.
Default Inventory File Scan Rules can have the check-box marked for "Report size/file count only". Any rule with this option will only collect the size and file count, even if there is a second rule without the box checked specifying that all file details should be collected.
If you uncheck the box, it will capture all details, including the size and file counts. It is not necessary to have more than one rule to capture all data. If you have not created a second rule, look for an existing, default rule that may specify that file type to only collect size and file counts.