N360 Online Backup Error: Another Backup operation running?

Been with Norton a long time. Currently running N360 Premier v 21.2 with automatic online backups set.  Running Windows XP SP3.

 

Lately, I'm getting Backup Error: Pending with Detail: "Another Backup operation is running. Please try again later."

Checked Task Manager - nothing there to indicate another backup running.

I have not used 20% of my online backup space.

 

What could be causing this backup error and how do I fix it?  Could Verizon Cloud possibly be interfering in some way and how?

Online Backup is essential feature of N360 for me.  I learned the backup lesson the hard way and don't want to go through that again.  Can I get some help with this?