Just fo fun, I did hook up a scope to verify that data was indeed transmitted over the TX line, unfortunately not decoded by the AD2PI device.
We see the 'heartbeat' clock coming in, as well as datastream once in a while when a status is being provided, but the device doesn't see it.
That's really too bad.
I sent an email to the support channel. A ticket number has been assigned to my case. Pending for further action from engineering now.