Altium designer: GND plane Polygone does not reach a vias array
You need to add a new rule to your PCB:

You'll see in this picture, I've added a rule which I've called PolygonConnect_Vias and it is located under Plane->Polygon Connect Style.
In this rule I've slected 'Advanced (Query)' for the First Object Match, and typed 'isVia' in the Full Query box.
Then for Connect Style, I've chosen Direct Connect.
Repour your polygon and you should see it covering all of the vias instead of connecting to them with thermal reliefs.