The AV button is a tricky one. There are certain buttons (usually identified by the ellipse [...] following the name) that have a unique and uncorruptable constitution. As soon as they are touched or looked at in any way, they cease to work. The problem is a known one and will likely be hased out in a coming software update. There are apparently characteristics to the command that are not included in the values that a programmer can affect.
That being (awkwardly) said, I have made my own life easy since my setup requires lots of AVing, and simply given myself pre-AVed commands for things. You can do this by making the AV command inherent in the IR string. It will look like this 00.000.RADIO.TV for AV TV, or 00.000.TV.CD, for AV CD depending on which master you're acting on. In my home, I have an MX with a BC9000 connected via datalink. To use the speakers attached to the MX, I would issue an audio command to a video product. This way my AV button is unneccessary.
I can't imagine that helping, but there it is all the same.
There is scarcely anything in this world that some man cannot make a little worse and sell a little more cheaply. The person who buys on price alone is this man's lawful prey. - John Ruskin