Hi @marcgreen11,
Amazon is a bit notorious for large file upload quirks. They tend to throw exceptions on large file uploads saying they failed. Since they don’t have an upload resume API available to use, the upload has to restart from scratch when this happens.
This post has more detailed information about this: Recurring problem with upload to Amazon drive
In addition to the suggestions in the above post, I believe that Amazon’s client utilizes their unreleased upload resume API, so you can also try using their client to get these last large files uploaded.
If you send a diagnostic from the odrive menu I can take a deeper look and confirm.