* Why do you say that the net you have highlighted is assigned to GND? You have not posted any image that shows that to be the case. * The cross on the GND net in the Design Manager indicates that there are one or more connections to GND that are incomplete such as a GND pin on a device or a GND symbol left unconnected.

* I selected GND net in the left, wires which is assigned to GND (on my oppinion) became colored red. Other wires are stayed green. * I got it, how to find it

I have solved this problem. The problem was about GND pads which were hide in schematic module. I don't know, if it right behaviour, but it was unexpectable.