Why is the enemy Artillery unit not seen as encircled?

[Granatenwerfer100]

Please look at the screenshot, at the Artillery unit marked with a broken white circle.
The screenshot is taken from the map Gijon, AO Spanish Civil War.
Left and right you see a large river. Large rivers are detrimental to supplies. So my question is why is this unit not marked as encircled?

111111.jpg (719.24 KiB) Viewed 831 times

[George_Parr]

The edge of the map works as a supply source. Since there is nothing that blocks the path to the edge, the unit is in supply.

[scorehouse]

Its been that way all along it's just sometimes its hard to delineate the boundaries