Specific account backups not downloading- very confusing

I realize that this is likely not a cpanel issue, but I am posting this in case someone has an idea of what could be causing this backup transfer problem.  If anyone has any clue as to what might be happening here I'd be grateful for the insight.  I'm wondering if cpanel saves certain account backups in different ways that might make Google Drive suspicious?  I'll try to explain...

I have two cpanel servers that backup to Google Drive each night. The backups all arrive as expected to the GDrive. I then use my NAS at home to sync from that GDrive folder and download a copy to the NAS as well ( maintain two backups, blah blah).  I can't have cpanel reliably offload the second copy to the NAS directly due to bandwidth and dynamic IP issues. 

Everything makes it to GDrive fine, but the same specific account backups fail do to be downloaded from GDrive to the NAS each and every time.  It doesn't matter which day's folder, it just won't download those specific accounts to the NAS yet they download fine if I download them directly to my home PC from the GDrive app.  

There are around 40 accounts on those servers.  Most are 1gb or larger and they all transfer just fine.  The only things that are related about the ones that won't transfer are:

1)  They are very SMALL backup sets.  In each case the only accounts failing to download are under 100mb in size.

2)  They are accounts that do not have a CMS installed in them.  Mostly just plain HTML or in one case a site built using the old weebly builder.  In one case the account is only used for email and has no web files of any kind.

The error I get each time is "Failed to read source file".  Any idea of what might be happening here or if it somehow could be related to the backup file formats?