In order to be able to investigate Cloud Sync issues like this, we need to be able to see log files. To do so, please:
1. Enable [debug logging](https://support.plex.tv/hc/en-us/articles/201643703)
2. Restart your Plex Media Server
3. Create a Cloud Sync job for a single item
4. Let it try to go through the processing then upload process
5. Grab the "Plex Media Server.log" file and attach it here
Without log files, there's basically no information to go on.