I've just gotten the Hexa back in the air after spending 2 months (!) to finally get a prop balancer that wasn't way out of balance itself. I notice in position hold, that it will rock in the front to back direction by a couple of metres pretty constantly. When I look at the logs, they look fairly clean, except for the ACC X log, which is quite noisy.
What would normally cause this sort of noise? Prop off centre? None of the props seem to have any lateral play around the hub when they're put onto the motor shafts. I spent a very long time balancing the props and hubs and am confident they're well balanced. I find it weird the vibration is only showing up on one axis.