Helix 3.0—"THE ALONG CAME POLY UPDATE"
3.0 for Helix Floor, Helix Rack, Helix LT, Helix Native, HX Effects, HX Stomp, and HX Edit is now available.
Any chance your global settings --> 'EXP Pedals' --> 'EXP 2 Pedal Position' parameter setting has changed since you updated? Depending on how you had it set before the update it can cause unpredictable volume changes afterwards from one preset/snapshot to the other if it is not the same.