The map "Auckland Domain, ältester öffentlicher Park in Auckland" on this page (left side) contains a geomask with external data. The object on the map is not shown, and the zoom is also not correct. The object is shown when you open the map in full size.

On the page
{F35263938}

Full size map
{F35263955}

The problem does not exist when a geoshape instead of a geomask is used.