I needed to do some experimenting to get this to work.
After clicking MIDI OFF to change mode to MIDI ON, I also had to click DIAL SELECTOR before I could click on a colored circular button to activate MIDI mode.
If I was actually doing this correctly, perhaps the instructions should be changed to reflect the need to click DIAL SELECTOR.
Exist multiple ways, to switch between modes.
Not always need click dial to change of MIDI mode, that is one way, another way is assign MIDI to hotkeys, in that way you can instant switch form one mode to other.
I send a private message to your e-mail, please check.