Jim Simon wrote:What are your GPU settings under Preferences>System>Memory and GPU?
GPU processing mode was set to CUDA. I tried it on Auto - no difference.
GPU selection was set to Auto but there's only one card and it was that one ticked in the box below.
Also worth noting that selecting the Youtube, Vimeo or Twitter presets (at any resolution) doesn't change the export settings at all, not even the resolution.
This all worked perfectly in 17.0.