So you are telling me that the rate in which a supply goes from 0 to 9v when powering up is the cause of this error? This doesn’t make sense. If this was inrush current, maybe I’d understand. But once the supply has settled, the pedal should just boot. I’ve never heard of this ever. What other pedals than EHX have this issue?
I had the same problem with a C9 on a Strymon Zuma supply. I tried multiple C9’s and none would work with the Zuma. But they of course worked with the 9.6V EH supply.
I found the POG2 worked fine with the Zuma, and swapped to that. I’m in the process of making a little adjustable voltage regulator to take the 12V from the Zuma, and dial it to 9.6V to see if that fixes it.