Re the recirc fans (Guess mode on..) . Mostly, you will enter high flow following pack failure of the opposite pack. Regulations require a certain volume of FRESH air per pax, so if on a single pack the recirc fans are on, maybe Boeing worked out that the volume wasn't guaranteed. Hence, they get inhibited? Maybe? (Guess mode off...)
I'm not sure having the recirc. on/off will make a difference to the fresh air volume. My guess would be preventing recirc. air from getting to the flight deck in the case of the left pack failing.