Replay Gain Missing

The Replay Gain option disappeared from Music Options.  My firmware is 2.01.35p, but I thought I had version 1.  Could I have accidentally installed the wrong firmware?

You can’t put the wrong firmware on a player.  If you have a v2 firmware, you have and always have had a v2 player.  The V1 uses a different CPU that doesn’t understand V2 firmware data.  

That’s good to know, but why did the Replay Gain disappear?