Garage Band: Tracks silent and grey but no tracks are solo'd or muted.

Garage Band on MacOS Mojave:

Every track but one is silent, but no tracks are solo'd or muted. All regions on the silent tracks are grey as when working with solo'd tracks; cursor and time display unusually yellow. Was working with a software instrument in piano roll when this happened. I suspect I have unwittingly turned on an unfamiliar setting, but have no idea what or how. Please see screenshot.