Well I am officially confounded. Seems like your betting beam power all the way to the nozzle, and height of focus is spot on. High Voltage connection looks solid, and I can see the beam energizing. Did you try flipping the focus mirror? maybe yours defies the laws of physics and runs backwards, stranger things have happened. and was that tape on the nozzle tested in all four corners of the gantry? (will show beam intensity is even across bed) Short of that I would guess bad tube/power supply. When mine died it still lit but had no output at all unlike yours.
Well now my machine is making a lier of me. But I upped by table hight by 3mm and is cutting well. Or at least good enough.
My laser has digital readout as a percentage
I cut 3mm MDF at 6mm sec at 18%
Assuming your meter is 23mA max then it equates to about 4.1mA