Using SKTexture(imageNamed:) in a Swift package

I'm trying to convert a Mac game Xcode project to a Swift package. I can't get the SKTexture(imageNamed:) init method to work in the package though. I have some other resources, and they load successfully via Bundle.module. All the resources are listed in my Package.swift with:

resources [ .process("Resources/pathname..."), ... ]

I tried leaving out the PNGs in case SPM has a special way of handling them, but it complained, and it didn't fix the problem, so that can't be the reason.

Is it just not possible to use this convenience initializer in a package? It's not a show stopper, because I can load an NSImage with Bundle.module.image(forResource:) and initialize my texture with that, but it would be nice if the convenience method worked.
Using SKTexture(imageNamed:) in a Swift package
 
 
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