Created attachment 101083 [details]
Generated result showing the problem
I witnessed this behavior a couple of times: if you have new image pixel tests, the |images| link in the final generated report do not work properly and link to the *-diff.html instead of the *-expected.png.
Sounds bad. :(
this appears to be working now. It's likely this got fixed some time in the past 11 months, but I have no idea when :). Please reopen or file a new bug if you still see an issue.