Sorry not seen your post earlier. If this is still happening, could you look in the temp directory (probably /tmp for your platform) looking for Plex/Uploads directory and see if there are partial upload files. Also would be good to get both sets of logs - server verbose logs as you have done now and plex for iOS logs as well as the directory listing for what is in the temp directory for uploads
The file is tripping on is a 70Mb video file with date/timestamp of 2018-11-04 21.00.06.mp4 Look for all videos for that day as i am not sure if there is timezone adjustment.
I suspect there was an interrupted upload and a partial file in temp and that there is a bug with resuming the upload. Checking what we have in tmp would give the extra clues
