When a job is running, a percent complete is displayed in various places in the UI. However, if thinly provisioned disks are being used, the calculation is misleading. The calculation is currently [bytes read] / [maximum size of disk]. If I provision a 5 TB disk and have 6 GB of data on the disk, after reading 5 GB Veeam B&R might tell me that the job is 1% complete. Then when that 6th GB is backed up, the progress will jump to 100%. A more accurate calculation would be [bytes read] / [actual data size]. Veam B&R knows what the actual data size is. It displays that in the Action grid.
They're not in my calculation, but it doesn't look like they are in B&R's calculation either. 3.4/5.0 = 68% on the nose. In my experience, they get stuck into 0% or 99%. I can understand why. It can be hard to predict how long something like an index will take. But it is easy to know that a disk has been thin provisioned. Any use of disk read in the algorithm will be more accurate if this is taken into account.