For slow attack done with fade, I’ve discovered the easiest way to set this up is avoiding LFO Wave ENV, and using Square instead, with LFO Rst on and (crucially) LFO speed set at 0 so that the LFO does not start to cycle. Combine that with Vol/Dist low or zero, LFO Dest of Vol/Dist (depth say at 50) and LFO Fde at about -30 is a good place to start experimenting