You can check this in VCDS next time too, my rpm needle does not move during starts but vcds always gives a value. I had a no start 2 days ago when I forgot to plug in the sensor plugs when I moved the loom, you cant feel the relay pull when you turn the key and it will not fire :-) or just look in vcds block 1, it will stay static.
That was exactly my case, but I just didn't think VCDS updates during cranking...