LR CC: 2015 2.1
OS: OS X 10.9.5 (13F1112)
This could be caused due to the display adapter drivers.
Please follow the below steps to disable the display adapter.
> Launch Lightroom
> Go to Lightroom > Preferences.
> Go to the Performance Tab,
> Uncheck ""Use Graphics Processor
> Restart the computer
> Restart Lightroom and see if it works.
Just tried that. same issue. Thanks.
Please roll back to Lightroom CC 2015.1.1 (Lightroom 6.1.1) and check for the issue.
Refer to this document on how to roll back to Lightroom 6.1.1 (Instructions to roll back to a prior update version).
I have the same problem with Lightroom CC 6.4. Video clips do not scale up to the full picture cell in the slideshow. Exported pictures and video clips from Lightroom and imported them to "Pictures for OSX" and there everything worked as expected (pictures and video clips scale to the same size). But I wasn't able to hear the audio from the clips in the Pictures slideshow
Must be a bug in Lightroom where the video doesn't scale up to the correct size. I have a Mac with Retina display. And if I adjust the resolution on the display to lowest possible, then the video clip fills the cell.