Can't Play Local Playlist through Other Devices

[rxf]

Premium

USA

Nexus 6P, Pixel 2XL, Roku 3, Roku Stick, PC  (Win10 Pro)

I've got a local playlist [Neil Cicierega -Mouth Moods] made of mp3s that resides on my two phones and desktop. I can play them on all 3 devices. If I try to "Connect to a device" to either of my Rokus (Roku 3, Roku Stick), the device is grayed out with "Can't play this right now". This happens for both phones and my PC. 

I can play any other native Spotify content to my Rokus. 

How do I get this to work?

[rxf]

Anything?