Back-Up to Cloud Stalls: Access to the file or folder is denied

Hello,

I have a series of backups created going from our drobo fs to the acronis cloud. They are staged to fire off every hour throughout the night. Because of the volume, it seems better to chunk it than do one big backup. I am using NAS pathing.

If I have a file open through a mapped drive letter on another computer in our network that is in one of the backup sets, that backup set will stall with the message, "Access to the file or folder is denied." Then it sits there waiting for manual intervention and none of the other back-ups run. I am pretty sure that the same thing happens with local back-ups.