I’ve noticed that every time I install a new application, the icon does not show up in my Applications stack. So, in order to fix the broken application icon, we have this temporary solution:

Open up Terminal (found in the Utilities folder), type killall Dock (make sure “D” is capitalized) and press enter. This will restart your dock and fix the application icon. You will need to do this every time you install an application and find the application icon broken.