Thank you all for the hints. I did multiple things, still no success.
I was sure the IR emitter is working as the other one (on the same lead) was properly controlling another equipment. Of course I was wrong... The one emitter on the Anthem was not working at all. So I replaced with a good one, checking with my iPhone that it emits IR signal. (I had to learn though that only the front facing camera of the iPhone 'sees' IR, not the back facing.)
After having a proper emitter on the Anthem, I tried Normal as well as Low output levels, both with the Anthem manufacturers HEX code and the one learnt from the original remote. Still nothing. I keep trying....