We have an I3 and the right hand side Playback w/Faders Bank will not control groups. The left Playback w/ Faders group one will control a group perfectly. However, if I drag that same group into any position in the right hand bank I get zero fader control. The flash will bring the group up to full.

What am I missing?

i had a similar issue about 5-6 versions of the software ago, so if you're not running the current software i'd suggest downloading it

if you are running the latest version, is there a clip active that's over riding the group (ie. intensity set to 'off')? this can cause that issue as well

if you upload a copy of your show file it can be tested on other hardware to see if it's your console or a software bug