motor current sense question

That does not matter. What does matter is whether I_source includes the current that goes to the capacitors. Remember my sentence "The I_source I have been talking about is the one that you would measure right at the inputs to the full bridge"? Your corrected sketch still does not clear up the confusion (you drew an arrow over an intersection between two wires, so I really don't know what I_source means for you, yet). From your scope screenshots, though, there is no chance for mistake: Your I_source does include the capacitor current, which is what I had been asking about. The capacitors are the reason for the mismatch (between I_source_peak and I_motor_peak) that surprises you. Kirchoff's law states I_source = I_capacitors + I_full_bridge. I_source and I_full_bridge don't have to be identical anymore, if you insert capacitors.

Best,