Not sure if this has been submitted before, I couldn't find anything, BUT it's the ONE thing I think is missing from the HX Effects, and that's the ability to use a Expression Pedal with a toe switch.... It can be done in the Rack Mount Helix and HX Stomp so why not bring it to the HX Effects, assuming all that's needed is a software change....
any way... if you like the idea... give it a vote up
https://line6.ideascale.com/a/dtd/Toe-Switch-function-for-HX-Effects-Expression-Pedal/946748-23508#idea-tab-details