Jumpy and shaky video quality when downloading video

Hello,
I have created two videos this evening using uploaded video from my Nikon D750, which I have done several times before. The video quality looks great in the timeline and on playback in Adobe Express.  When I download the video, some of it is fine but most of it is "jumpy" and shaky.   Like the video freezes and then leaps ahead and a few milliseconds, creating a very jarry playback.  I've tried re-downloading the files multiple times but have the same issue every time.  I also tried playing it in different media players, but it truly seems to be a problem with the video file.  Again, the original videos are NOT shaky and it plays back just fine in Adobe Express.  It's the final download that seems corrupted.  Help?