Solved Rendering video in 4K

I have shot some movie footage in 4K format and imported into Movie Studio 14 Platinum. It is possible to set the project properties to match,(i.e. 3840 X2160.) but when I want to render the project under the "MAIN CONCEPT MPEG-2" setting in order to burn to a disc, I find two problems :

1. I cannot set the output to the format 3840X 2160. The highest quality I can find is 1920 X 1080 under Blu-ray disc. How can I render with the output being in 4K ?

2. When I render using this setting, the resulting file format is an ".m2v" file. I have previously rendered with FHD 1920 X 1080 settings using the MAIN CONCEPT MPEG-2 format but with the Program Stream PAL Widescreen Template and the output is in an .mpeg file with which I have no problems. I sometimes load this rendered file into Nero 2016 to actually burn the disc because I find it simple and I like some of their menu options. However, with an .m2v file, I have a problem when using Nero because I get an error message to the effect that it does not recognize the audio file format. Any suggestions ?

4K video is not supported by the Blu-ray format, that is why it is not working.
There is no way for consumers to make 4K Ultra HD Blu-ray discs at the moment.
4K Ultra HD Blu-ray optical drives only allow for playback, not burning 4K as well.

Only the big Hollywood Movie Studios can replicate 4K Blu-ray discs at the moment.

With your Nero problem your m2v file is video stream only. There is no audio. You need to render this separately. DVDA will then pick up both but Nero won't. Nero needs a file that contains the audio.