INFO Waiting for file hashing and copying threads

I have a client/machine that does a backup of a MSSQL database set every two hours. About 6 databases totaling just less than 100gb. Most times the backup takes about 30 minutes. A short amount of that time is actually grabbing the files and the rest sits on the “INFO Waiting for file hashing and copying threads…” bit which is fine. However about once a week it hangs on the “INFO Waiting for file hashing and copying threads…” for HOURS. The server itself is not very busy and right now this is the only backup that runs during normal business hours. Any thoughts? TIA

Bill

Edit just to add. This seems like a server side issue. During this time the client claims that the backup is finished. Also Server storage is a solid state driver array, really fast. no antivirus at all.