Sizing and positioning of isometric maps incorrect/inconsistent

[Krumelur]

Using CCTileMap with non-squared dimensions displays the map incorrectly. See screenshot:

The map above is 28x33 tiles.

A squared map is rendered correctly:

In both cases, the VisibleBoundsWorldspace returns the following values:

{CCRect : (x=0, y=0, width=1920, height=1080)}
    Center: {CCPoint : (x=960, y=540)}
    InvertedSize: {CCRect : (x=0, y=0, width=1080, height=1920)}
    LowerLeft: {CCPoint : (x=0, y=0)}
    MaxX: 1920
    MaxY: 1080
    MidX: 960
    MidY: 540
    MinX: 0
    MinY: 0
    Origin: {CCPoint : (x=0, y=0)}
    Size: {1920 x 1080}
    UpperRight: {CCPoint : (x=1920, y=1080)}

The visible bounds match the design resolution of 1920x1080 I'm using.

Related to this problem: the CCTileMap is always using the complete screen, even if it gets added to a CCLayer with smaller dimensions. I tried the following:

var smallLayer = new CCLayer(new CCSize(500, 500), CCClipMode.Bounds);
smallLayer.AddChild(tileLayer);
gameLayer.AddChild(smallLayer);

I'd expect the tile map to be clipped to the smallLayer bounds but still the map renders exactly as seen in the screenshots above.

A test project can be found here: https://github.com/Krumelur/Carcass/tree/issue_tilemap_offset