Hah, and you forgot to mention that the OT will not send the message if it is identical to the last one it sent.
So in this situation it will look like it doesn’t work: You start the sequencer, the CC’s are sent to the external synth, which changes accordingly as expected. Then you change the patch on the external synth manually (for whatever reason: because you’re jamming, because you edit sounds, whatever). When you restart the sequence on the OT (can be hours later), the CC’s will NOT be sent. This is not a bug, but default behaviour and can be very disturbing…
For this reason (I like to change patches, or patterns on my Digitone manually while playing) I do not use any Elektron device for initial patch/pattern changes. I prefer to use a external Midi Controller.