Cannot make an m4v file with Dolby 5.1 audio using Compressor

There was an old problem listed in this discussion site with the title: Getting dolby 5.1 surround with FCPx and Compressor

No answers or other comments were replied. I now have the same problem, restated here.

I make a mov file using FCP with audio set to surround. Looking at the info for this file, it states there are six audio channels. If I use any FCP options to make an m4v file, the Dolby 5.1 is replaced by stereo. Again looking a the file info for that m4v file, it states audio is stereo. Using Compressor on my mov file, I select the transcoding selection to be Apple Devices HD and in the audio settings of the inspector at the lower right, I select the Dolby 5.1 option. After Compressor finishes, a look at the file info again says that the audio is stereo, not the 6 channels of the original mov file.

How do I get a HD video file to play on my Apple TV 4k with Dolby 5.1 audio?