I I have LR 6 on Windows 8.1, Intel i5 with GeForce Ti 650 boost. The slideshows render ok except for captions used as text overlays for each slide. Similar slideshows from LR 5.7 are perfect. I have tried with and without the pan and zoom, and used other meta data, eg title and file name. In slideshow creation all looks good, then in PLAY or PREVIEW only the first few slides have high res captions then they deteriorate. Once exported to video using the high quality setting and 1080p output ALL captions are poor.