UPDATE 19.August.2020: Problem solved, please re_download Alps, Alps_Ost, Austria
Mapsforge, the tool that finally renders the maps, unfortunately only allows 15 tags per object (path). If this limit is exceeded, white (empty) tiles appear on the map without warning.
This is currently the case east of Grossarl in Austria.
Reason are several paths on which a lot of tags for summer and winter sports have been mapped.
The only viable solution is to separate the winter sports tags into new objects (paths) to be created.
This means a complete new handling of the routes/paths resolution of the winter sports tags. There are no ready-made tools for this = it has to be coded in Perl.
I hope that by the weekend new maps for