Local and streamed songs do not shuffle correctly together

[joelw]

I have a playlist with both local and streaming songs from the same artist. The local songs are not available on Spotify, and thus do not match with any albums on there. When I shuffle the whole playlist, all of the local songs are shuffled first, and then all of the streaming songs come shuffled after that. I.e. there streaming and local songs are shuffled separately, but do not mix with one another. Obviously, this is not what I want. I I want all the songs to shuffle regardless of their source. How can I fix this?