My tests are showing that it in addition to
“Delete all AssetBundle content that has been cached by the current application.”
it also clears the ProceduralMaterial disk cache.
After iterating on device through lots of seemingly correct ways to use the vague ProceduralMaterial interface only to learn that nothing I did with it would ever make it work correctly, I’m more than a little frustrated. It would help if the ProceduralMaterial docs were more explicit about in-memory cache vs persistent, on-disk cache instead of just referring to “cache” everywhere. There is also no mention of whether a disk-cached material needs to be rebuilt or not (apparently, it does).