I have just installed Lightroom 6 ( I have had every LR version since the original 1.1) everything works fine except the export video part of slide show. When I playback, the top half of each photo is offset to the left about a 30th of the picture width. The lost piece is inserted to the right hand side at the top.
If I preview the video there are no problems but if I play, then the problem occurs, but also it does not release after the end screen and I have to force a shut down of the program to regain control.
One other thing I noticed is that any pictures that had been cropped from the original 35mm format do not have the problem nor do any of the quicktime videos included in the exported video.
The actual production of the exported video also takes much longer than it ever did in LR 5