Some riders prefer to connect their bike-based power meter independently from their smart trainers which includes power pedals.
A common issue is that only half of the power is being reported as Velocity has been connected to the wrong pedal.
Most pedals have a "Master" or "Parent" pedal and a "Child" pedal. The "Parent" pedal will pick up the power and cadence data from the "Child" pedal and report the composite data if connected and configured correctly.
This is where it gets tricky. For most pedals, they need to be configured in the manufacturer's app to send the composite data from the "Parent" pedal and that pedal needs to be connected to Velocity. In many cases, the "Parent" pedal is the left pedal.
The following is information for some of the leading pedal brands/models:
PowerTap
PowerTap
Stages
Stages