The developer found the problem:
DTR wasn’t being asserted on the USB-CDC connection from the Xojo app, and was therefore failing a connection check before sending the status response. Not sure why that doesn’t affect more output, but hey ho…
Looking at your code, I tried setting
SerialConnection1.DTR = True, but no change. Then google led me toSerialConnection1.DataTerminalReady = True, and that seems to have done the trick here.
That’s why it didn’t worked for me as I tried SerialConnection.DTR = True as well.