Anthem AVM 60 full range front and sub doesn't work

See if you have separate crossovers for your L/R and your subwoofer.  If so, set the L/R crossover "frequency" to off, and then set the sub crossover frequency to whatever value you'd like.

I did that.. I set the L/R crossover to OFF but the sub never gets a signal.. I have upgraded to the latest firmware too.  As soon as I set the front L/R to 40hz, then the sub gets the signal to turn on.  I've tried several times in different ways and setting the fronts to full range kills any sub signal from the sub outs.

Agree, any processor or surround receiver i have used delivers full range to the fronts and no content to the sub when Mains are set to Large and no crossover is applied