Map Display problems

Kurviger Liberty Map: empty tiles when zooming in.
With the new design I got quite often empty (grey) tiles within the Kuriviger Liberty Map. Zooming out again and enough brings the tiles back. But with zooming in they are lost again. Moving the map (with the hand) does not help.
Routes/Tracks however are shown completely always.

This problem does not occur with other maps.
The probme occurs with Chrome and the new Edge.

Haven’t had the problem within the old design …

What could be the problem?
Thanks, Ernst