I may be misunderstanding the functionality here, so I'll describe my goal and expectation, along with the resulting issues.

I have a regression test that compares screenshots to a baseline. I would love to show those side-by-side. They are currently stored in separate root directories with the same subdirectory structure. Something like:
path/to/screenshots/base/testcase/browser/resolution/a.png
path/to/screenshots/fail/testcase/browser/resolution/a.png
path/to/screenshots/new/testcase/browser/resolution/a.png

I configured the common base dir to be path/to/screenshots/
The resulting structure looked good, but the images were broken. I had a nice tree like this:

-test A
--browser 1
— Resolution a
---- root: base (img)
---- root: fail (img)
---- root: new (img)

Turns out the resulting urls used the common base as the starting point, which is not where the actual archive is, so all of the images were broken. The resulting image URLs were:
artifact/screenshots/base/...
This leaves out the rest of the actual path to the image ("path/to" from the above example)

I also noticed that the link for each image did not go anywhere - I had expected being able to view the larger image in the lightbox (this did not work even after I got the images to display). It would be nice to have the link function even if the JS is broken/disabled.

In order to get the correct URL for the images, I had to make my base dir match the base dir for my build ("path/" using the above example), but this not only yields a much larger tree than I'd like, but also doesn't group the images the way I'd like, since they all have a common root.

Is this perhaps a misconfiguration/misunderstanding on my end?

Thank you for your time and effort on this excellent plugin.