Surface Scan - 3TB HDD ... Has been going on for over 31 hours

I started Surface Scan (TT8) on my 3TB Seagate HDD yesterday afternoon. Now (see attached), the UI indicates 5% completion (note that the time counter resets after 24 hours to 0:00:00).

Is this normal? Whats the expected time to completion for a 3TB drive?

Thanks