To begin, I must say that I am very impressed with Emby so far. I have been a Plex user for years, and just got tired of the lack of flexibility when it comes to music collections. I stumbled on Emby, and it does exactly what it should do. It gives you a simple way to access large libraries of music without making any assumptions about how you have it organized, or forcing you to completely rearrange it. My collection of music is all MP3s, and is organized by genre. I like to have playlists for each genre and listen to them randomly. Emby handles that in spades. It works flawlessly in the web interface and on the Roku.
I have run into a small issue that I'm hoping you can easily fix. This happens on both the web interface and Roku 3 (Emby shows it as SG 3.0.193). On the web interface when I'm viewing playlists and select "Instant Mix" option, nothing happens. On the Roku when I open a music playlist, then select the "Instant Mix" button, it pops a "Playback error". This happens on all 5 of my playlists.
My workaround is to use Shuffle for now, which is perfectly fine when on the web interface. It just takes a few more steps on the Roku since I have to play the playlist first, then shuffle it.
I am running the latest release of Emby Server (184.108.40.206) on Windows Server 2019.
Let me know if you need anything else.