On Source View, I need to see the differences between the current and some past version of a given file. I'm trying to find the originator of an apparently errant insertion of source code. when I select "Diff" from the upper-left-hand corner button/menu (from Source to Diff), expecting (as I thought it used to in the past) to see a difference between current and the immediately preceding version, I instead get nothing. The browser doesn't "chug" with the timer icon for the cursor, indicating it's not stuck processing, it gives an updated, VERY long and cryptic URL, but the page itself is blank and displays nothing.