There is a brand new 'Behavior' parameter in the 3.15 firmware, and it profoundly impacts how auto-engage operates. It is found with the rest of the parameters that appear under the 'Bypass Assign' section when you set up auto-engage by changing the 'Switch' parameter from "EXP Toe" to "EXP Pedal 1,2, or 3", "Variax Vol" or "Variax Tone". This 'Behavior' parameter may impact the operation of presets with a block set up to auto-engage, designed prior to the 3.15 firmware. The easiest problematic