Calculating Avamar replication (clone) individual client job durations

Slowly going mad trying to calculate Avamar replication (clone) individual client job durations. Basically, I just want to know the difference between the Clone End and Clone Start times from the Clone Job Details data source, and display it in its own column (and maybe sort it).

I have gotten as far as subtracting the Clone Start from Clone End times, but the result I get is in a date format, not a time format (12/31/69 7:05 PM, for example).

No function (such as Time to Duration) or parameter change (Date to Duration) seems to be able to change the value from the 1969 date to anything else.

I've tried other approaches but nothing else comes this close, so I'm trying to stay with it.

There isn't any info in the Custom Reports guide on this and because it's the Clone aspect, it doesn't seem to work with any of the Extended Job operators (which appear to only work for Backup, and on fields that are specific to Backup).

What am I missing here? All comments/feedback appreciated - thanks.