I found a workaround since this seems to be a bug on macCatalyst.

It seems to be a requirement to add individual scales for an asset to appear on macCatalyst at all. It still fails to use the rights asset, but at least will revert to the default asset as long as all scales have been provided. If a single scale is used, there will be no image available on macCatalyst.

I therefore added the macCatalyst image as the default asset and then added an additional iPhone and iPad asset. This will correctly detect the right asset to use in iOS, but macCatalyst will always revert to the then correct default asset.