Swift Package compilation issues

I'm working on an iOS project that uses Swift Package Manager to download and link a private package to it.

The package is developed internally in our company, and it contains over 4000 files.
The package creates namespaces using extensions, eg:

Code Block /* Core.swift */
public enum Core {
	public enum Blobs { } 
  /* More enum declarations here */
}
/* SomeBlob.swift */
public extension Core.Blobs {
	public class SomeBlob {
	/* implementation here */
	}
}

Code Block
/* Core.swift */
public enum Core {
public enum Blobs { }
/* More enum declarations here */
}

/* SomeBlob.swift */
public extension Core.Blobs {
public class SomeBlob {
/* implementation here */
}
}

The issue that we're facing is that we are unable to access all the classes, structs and enums from the Package, even though they've all been declared public. We are only able to access approximately a quarter of the files (up to the ones beginning with the letter C).

Has anyone had this issue before ?
Any suggestions are welcome.
Thanks in advance :)