Mark Net in Virtuoso-L

Hi all,
I have troubles using the Mark net tool, maybe you could help out.

In this example for the test I try to highlight a simple net (that does not propagates too much in the layout) called "pwr_i", here in metal 2 (purple).
I do: Connectivity > Mark net, and then press F3, and in the MarkNet Options windows go in Via Layers tab and -for the test- deselect all but (M2) (V2) (M3).

The result is plenty of other unattached signals are highlighted: in this example you can see the "en" signal (horizontal) and even the thick exclude layers (on the left) are highlithed as well...

What do I do wrong ?

Thanks for your help and best regards