OK, it looks like the meter is better than I thought.You certainly now more than me about this. I use this meter Amprobe NAV51. I always used it assuming it correctly does the power factor conversion.
It looks like it does measure the power.
It can also measure power factor.
What was the power factor (P.F)?
Also, check the amps and voltage separately.
The volts x the amps x P.F should equal watts.