I have a Samsung UN40EH5300 television, which has optical audio output. I am trying to connect it to an old receiver with analog audio input (2-channel, not 5.1). I bought a converter box for about $35, and this worked fine.
Until it stopped working. Not sure what happened, maybe a software update? Anyway, I tried replacing the converter, and the optical cable. I have spent MANY hours on the phone with Samsung support. No joy.
The 3rd-level support person finally said that what I was trying to do was unsupported (!) and that I needed to connect to a receiver with optical input. Which sounds an awful lot like "I don't know, go away."
it certainly does sound like the technician was saying "i dont know, go away" to me as well.
while it certainly may not be for the purpose the port was intended for (which was to connect to soundbars or receivers) such converters do work and are one of the only ways to connect an older hifi set up to newer hardware.
an easy test to do is to see if the converter is still working. grab a computer, dvd player or other device (as kane suggested above) and use your converter with it. if everything works then its a tv issue. if it doesnt then test it on another device as well. if it fails two times in a row perhaps its either the receiver or converter.
if the converter passes, its an issue with the tv exporting audio via optical. i'd check your settings to make sure its enabled.