The problem might be with CTRL 1 VAL 1. Try setting it to 127 (actually, anything from 64-127).
I just want to confirm that you’re targeting the Bypass (and not Toggle between Bypass & Active).
I’m not familiar with the workings of the ES-8. But it could be its switch action is set up as latching, rather than momentary. That is, ON with one press; alternating with OFF on every other press. You’d want ON with switch press; OFF on release.
It’s been a while, but I believe you can use PC or CC commands for Active, Bypass, and Toggle.