I'm trying to upload a new version of my app to the App Store using the 2018.11.08 version of AppGameKit and version 3 of Application Loader and it's failing to upload with the following message:
ERROR ITMS-90717: "Invalid App Store Icon. The App Store Icon in the asset catalog in 'XXXXX.app' can't be transparent nor contain an alpha channel."
The app icon image that I'm passing through the AppGameKit IPA export has no transparent parts in it. I even added a layer behind it with a solid fill and exported it again. I've been using the same app icon for all of the previous export/uploads with no problems.