Backup job stalled

Hi All

I have a backup job which is running but no data transfers are taking place.

The Elapsed Time is incrementing but the Byte Count remain static.
The transfer rate is showing as 2.00mb/min when it is usually between 500mb and 2000mb.
The server being backed up is showing the beremore job reading data in task manager but the file sizes are not changing on the backup disks in file explorer or the media tab in BE. There is stacks of overwritable media.

I have applied windows updated to all servers oncerned but jobs have run since then and have progressed at the normal speeds.

Any ideas where to look next?

Thanks