We have an issue with resizing images where the old dimensions are getting cached--I think in Glass' lambda cache. I'm trying to figure out how to clear it once we update an image. The cached value has persisted across multiple app pool recycles, recompiles, and iisresets.
So say we have an image that's 1400x700 pixels. We get a new source image that's a more reasonable 500x250, so we go into the media library and attach the new version. This updates the Height and Width fields on the Sitecore item as expected. We publish the new image and view the page to discover it now has a black box around it. The image is the new 500x250 version, but the cached lambda expression is still passing the old dimensions to the .ashx.
RenderImage call was originally in the format
RenderImage(x => c.CurrentItem.Image, ...), which we then changed to
RenderImage(x => Model.CurrentItem.Image, ...) and then
RenderImage(Model.CurrentItem, x => x.Image). All three exhibited the same behavior, even with an
iisreset in between.
I've also tried disabling the cache per Mike Edwards' answer here: Disabling the Glass lambda cache. Which, of course, makes me wonder if it's the lambda cache at all, although I'm at a complete loss for another explanation.
I am using Sitecore 8.1.