Why is synching Video files to LR taking forever?

Having problems getting Video (MP4) files I have uploaded to the LR Cloud to fully synch as cross all devices. While it does appear on the machine from which it was uploaded, it does not show up on any of the other machines I have it installed on or the mobile app. I discovered this when I attemped to share, via a link,  one of the files. While a shared link was created, the person I sent it to found that there was nothing there, apparently because the file is still uploading. Side note - I uploaded about 20 still images (DNG & JPG )at the same time, they went thru fine. I also, in frustraation, uploaded one of the video files into Google Drive, that went fine, took about 15 minutes. Meanwhile, same file, from the same souce (SD Card) is going on 14 hrs in