1. >>>>now I'm using Autocad 2017
But in the attached image I see 2018 version. I don't see issue with grid in the image. Have you managed to resolve it?
2. >>>>even if I'm on millimeters (Units) this is what I see
I don't see anything strange in the attached screenshot. Everything seems to be OK with units - decimal with 4 digit precision.

Maxim