The LFE fader is only available in “.1” surround formats (5.1, 6.1, and 7.1).
The LFE fader determines how much of the current track’s signal will be routed to the LFE channel. LFE faders in Track and Send windows can follow groups. The Pro Tools LFE channel is always full-bandwidth. For more information on how to use the LFE fader, see LFE Faders in Multichannel Panners.