Cory -- your icons should be located in a "package-assets" folder in the root of your project folder. We moved to that location over six months ago for all new projects. We tried to encourage users to move to that new location with older existing projects, but allowed existing projects to continue to reference the old location as a convenience. If you remove the icons via the GUI (they won't be deleted from your project, just from the GUI placeholder) and then try to add them back, the XDK should automatically create a package-assets folder and insist on adding them back from this new folder. Obviously, you'll have to then copy your icons and splash screens to the new package-assets folder before you can add them back with the GUI interface.
