Why doesn't Apple Watch Series 2 measure steps?

Question

Apple

I bought an Apple Watch Series 2 today, set everything up and everything works. Toward evening I came home, went into activity and the number of steps taken is zero, the number of kcal that I burned is also not shown. I tried to include walking in the training, walked about 100m, everything seemed there and the data went into activity.
That's actually the question, why don't they just track walking for the whole day?

Answer 1

Reset didn't help.
But it was fixed by updating to watchOS 4.