It seems to me that your problem comes from the ECO mode of the device.
I am currently looking for RS232 codes for this device. Is it possible to provide them?
To put in ECO mode, it seems to me that I read something of the style in the doc. It's often the same problem, once you're OFF, he listens to nothing. A unplug / replug make a reset and again (for only once) the device listens.
On Samsung, I found a +/- functional solution that consisted of hibernating.

Thank you for the documentation if you can share it.