Try one or both of the fixes found here. https://forums.wincustomize.com/436401/page/1/#3490071
0) backup your registry, just in case (I recommend also to create a restore point)
1) start regedit
2) navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer and expand it
3) find "Shell Icons" key (note: this key does not normally exist in fresh Windows 8 installation, I guess IconPackager adds it)
4) delete it (or rename it if you are not sure)
5) restart your computer
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Open: C:\Users\[USERNAME]\AppData\Local\Microsoft\Windows\Explorer
Replace [USERNAME] with the username you're using. Delete everything in that directory. This is the icon cache for Windows Explorer. After you do that, reapply the default theme in IconPackager.
Also, in IP settings, there are Repair Shell Icons and Rebuild Icon Cache buttons. Those may work after repeated tries with Win 8, they only worked for me after multiple tries and reboots on Vista and Win 7 so ymmv.