Not a caching issue. I have tried several browsers and incognito/private windows. It is unclear to me where the icons are stored, but the third party addons seem to be able to load the default correctly. I have not re-named the images or themes directories, I have set both images and themes directories to 777 in case. Where else could they be? All the other icons in the CP work, the only ones that don’t are the core addons and freeform pro.