Ha ha I take it back. I missed your second post.
I think you need to switch your ES5 to a gate/control mode.. not a toggle mode. The H9 almost always just wants a positive cc value to activate a function.
IIRC, It sees a, like, 63-127 as engaging the switch, and 0-63 as releasing. This is especially key to preserve if you want the performance switch function to work correctly. Sending 127 with one press and 0 with the next is suboptimal
The boss should be able to do it.. but if it cant.. you can also use PC messages to toggle bypass/active.. which should be foolproof.