[World Map is corrupted, how can i fix it?]

For some days now My World Map displays 2 large areas of "empty" regions when zooming in to where the region name is shown. Zoomed out the map appears to be normal, but once the region names are shown, all map details disappear except the region name and user-set markers such as events or residents. Two "empty" areas, each 8 regions wide run from north to south, one from the northern tip of Corsica down to just east of the southern tip of Satari, the other empty strip runs down near the left edge of the map.

Failed remedies: Changed graphic settings, reinstalled Phoenix viewer, tried other viewers, cleared caches, including texture cache.

Any help is greatly appreciated

[Part of my World Map is corrupted]

Part of my world map  around the Nautilus area is corrupted, some regions show only their name and green resident dots.

How can i fix it?