The
// Check for additional matching images
block starting at line 39 does look for additional images in the base folder for the product, so you certainly would need to have files in that location in order for ZC to know to use the ones in /medium/. That's some very deep code in there, and I can't take time now to decipher it all. I guess the relevant question is, how does the code snippet referenced in posts above know to operate on the right base name... I'll have to look at that in depth later.
Another point - did you ever get the stock additional images function to work properly? Make sure you are doing that right before you introduce other variables like individual product/category subdirectories or making the additional images use the medium file instead of the small file.




