Do you purge the first dose from the grinder? If not it’s because you’re mostly using coffee that was ground last time you used the machine, and the second shot is freshly ground, so you want to make your adjustments based on the second shot.
I don't purge no, but sometimes I'm only coming back to the machine after 20 minutes and it still behaves like that. Would the beans in the grinder mechanism change that much so quickly?
Do you purge the first dose from the grinder? If not it’s because you’re mostly using coffee that was ground last time you used the machine, and the second shot is freshly ground, so you want to make your adjustments based on the second shot.