OSX App - Associated file types and icons not updating (Launch Services)

Question

I have a mac app that will open ".png" file types. I am able to get the application to make itself the default app that opens ".png" files and double clicking the files will launch my app.

However, I can't seem to update the icon on .png files - it shows the default icon that is a thumbnail of the image.

I have a file called ICON.icns in my project, and the following block in the Info.plist file:

<key>CFBundleDocumentTypes</key>
<array>
    <dict>
        <key>CFBundleTypeExtensions</key>
        <array>
            <string>png</string>
        </array>
        <key>CFBundleTypeIconFile</key>
        <string>ICON</string>
        <key>CFBundleTypeName</key>
        <string>PNG</string>
        <key>CFBundleTypeRole</key>
        <string>Viewer</string>
    </dict>
</array>

What's weird is if I restart my computer, the icons do update, but after a second or so will change back to the system default.

Thanks!