Is there a way to report on custom File (Content Version) fields? 

Elaboration on scenario: Custom fields on Content Version are 1) available on the Content report type, but 0 results generate in report for File Type = QUIPDOC. 2) not available on File and Content report type, but able to generate 7 results with File Type = QUIPDOC. Custom fields are visible on the Detail tab of a File record page. Custom fields should be reportable according to Summer 17 Release Notes: https://releasenotes.docs.salesforce.com/en-us/summer17/release-notes/rn_files_customize_files_details.htm?edition=&impact=