Hey Leonard, I just loaded a Retrologue to a track and everything worked fine.
Please note this:
Live does call my CC121 script 10x a second. I use this to update the LEDs and the fader’s position. This is why you have steady outgoing MIDI traffic.
I also send the MIDI ping command that brings the live into the CC121. Without sending this ping command (every second), the CC121 turns off and the blue LED (Cubase Ready) starts blinking. This is how Steinberg locks-in the CC121 to Cubase, because Cubase starts sending this Ping command.
When Live is busy e.g. by loading a plugin or saving a project, it will not call the CC121 script and therefore the Ping command is not sent, and therefore the CC121 turns off.
So I assume that at your situation, something is blocking the CC121 script repeatedly. Maybe the Steinberg plugins are doing something that stops Live from calling the scripts. I assume that also other controllers will not work properly…? So maybe they are scanning the license or dongle or something else.