The default auto-discovery assignment for the receiver is not to use that command set. — Staff replied: “Should be fixed in the next library update in a couple days. We still consider that command set a bit experimental though until a software update that actually switches over to it.”
The default auto-discovery assignment for the receiver is not to use that command set. Especially for zone 2, that's definitely experimental. Make sure to use the set assigned by auto-discovery to ensure proper zone 2 behavior.