Dropbox Cloud Backup to My Passport Ultra 2TB

I have tried numerous times to backup all of dropbox in the cloud to a 2tb Passport Ultra using WD Smartware Pro. There is approximately 100GB on DB and I’ve used the FILE (not the CATEGORY) back up system and check all files. However it is leaving 80GB not backed up. Any thoughts on fixing?

What do these pending files have in common? Folder path? Privacy permissions? File extension type? Can the backup progress if you start from scratch (Meaning, uninstalling the app and formatting your hard drive to clean it)?

The things that did back up were photos and music. These files were an assortment of documents. I just purchased the hard drive and just installed the app…but could do that if you think it would make a difference. Thanks for the response too!

The files that are not being backed up are grayed out and are labeled as “system” or “excluded” depending on the screen.

But…they are just regular files…doc and pdfs mainly…