Hello keps,
In my region is the EVO not available yet, but I think the behaviour you’re describing can be explained:
The middle gear has the ratio of 100%, that means the cranks and the beltwheel are rotating with the same speed and the gear wheels inside of the drive are standing still.
In the 1st (78,7%) and 3rd gear (125,7%) the gear wheels are in rotation to achieve a different number of rotation between cranks and beltwheel.
I guess the rough sound you’re hearing are the teeth of the gear wheels which are rolling at each other.
Maybe the EVO gear needs some time for running-in.
Besides of the rough feeling, is there any kind of resistance while pedaling?