So I just upgraded to the new 2017 MPB, and am using FCPX. After I export to either 4k or Ori, the video plays fine in Quicktime, but when I import it into FCPX, regardless if I use proxy files or not, the playback screen is all black. Has anyone else had this issue? I've had great experience with my 2015 MBP, so I'm trying to see what the difference is. Thanks for any help!

Maybe your version of FCP cannot deal with the Wide-Gamut files that LRTimelapse creates by defaut. Try setting to "Standard Gamut (BT.709)" in the Render dialog and render again. Make also sure to not render with settings that show the orange warning in the render dialog. When you work with MP4 use 4K UHD and "Force output to 16:9" and 30fps. This should be safe for every program!