As I said, measuring the voltage causes current to flow. My meter claims to have a 10 Megohm input impedance. I just measured the current flowing when measuring 5V with the meter, namely 0.45 uA.
Solving for R:
R = 5 / 0.45e-6 = 11111111
11 Megohms which agrees roughly with the claim by the manufacturer.
Thus to measure 5V I am drawing 0.45 uA.
Measuring 12V I drew 1.2 uA, which agrees exactly with the claimed performance:
R = 12 / 1.2e-6 = 10000000
So you can't say "with no current flowing". You might say "with 1.2 uA flowing as drawn by my meter."