To complete te answer:
Play state is toggling the track into a green color in the playlist after being played for 30 seconds. Currently (unfortunately) it doesn’t work the same everywhere in Engine OS. This is what happens around the system:
- Playlists toggle played state after 30 seconds to green in list and auto update list
- Prepare toggle played state after 30 seconds to green in list and auto update list
- Streaming services toggle played state after 30 seconds to green in background, but do not auto update list and are not shown rightaway. You will have to exit the playlist and return to the list see the track marked green.
- History does not show green played state at all
- Files does not show green played state at all
- Tracks with total duration shorter than 30 seconds will not be marked green as played
- Tracks played under 30 seconds will not be marked green as played
Besides tracks being marked green in the playlists you will also see them in the History. In library view press History on the left side and navigate to the current set.