my mp4 file has zero bytes and won't open after I export to video. I'm using a MAC.
May I know the version of Lightroom you have?
Do you use Drop box?
Could you please change the destination location and then try to export.
I'm seeing this on windows with the latest Lightroom version, 2015.6.1. The exported file has zero bytes regardless of what video I try to export.
Retrieving data ...