As on Linux the HD Lossess/H.264 profile simply states.

properties=lossless/H.264

Yet when trying to render with this profile in windows we could only get a black/blank 60 second clip.

When changing properties of the profile to say
properties=lossless/H.264

We do though get results when we set the profile to say
properties=H.264

* Why isn't the lossless/H.264 profile rendering on Windows?
* If not using the property properties=lossless/H.264 what properties should
we try for lossless or new lossless H264?

Please advise

have you replaced the ffmpeg files with latest ones? (21 august)

ffmpeg-20170821-d826951-win64-shared.zip (search in google e take files in BIN)