ok after looking at the hydraulic schematic, electrical schematic, manual and service bullitens.
the key has to be off or the battery has to be unplugged in order for the e-lower to work. when on (even on auto off) the prop valve (which is normally open) is receiving voltage keeping it closed. so when turning the e-lower/L/H solenoid **** it will do nothing.
If you look up RSB OPR-07-001 it has a newer software that fixes this and will allow the truck to be lowered when ever.