Thanks for you answer, meanwhile I found solutions for my problems.
1.) It is also possible with the app to move the derailleur down to it's initial position, just do it in the "initial setup" menu (I got a mail from support with the instructions)

2.) Shifting to 46 sprocket is also possible now for me. My chain was too long and I had to remove one chainlink. I discovered this also after fiddling around for ~2 hours.

A short test ride today worked fine for me, also shifting under heavy torque on a steep section was no problem.

Hi,

Anyone here, who runs a wheeltop MTB derailleur (long cage) with a a Shimano XT 11spd 11-46 cassette, single crank? I installed mine yesterday (used cassette, new XT 11s chain) following the official setup video. The sprockets 11-37 are working fine but it does not shift from 37 to 46. Tried to increase the fine tuning value step by step but it didn't work. When I go over a certain value, the derailleur moves but immediately moves back, seem to be some kind of safety measure.

Anyone here who has experience or can provide the fine tuning values for this cassette?