Hmm. Seems my first reply went AWOL. Anyway.

First test:
After clearing cache, no map was visible. Ambiance background shines through overlay with PM controls.

Second test:
I had a false start. Stopped before downloading 100M of routing data, to save on my mobile quota, but then it did not work.
After getting that data, the world overview map did show, as did the Azores... Both OSM Scout and Mapbox Streets (default) seem ok.

So conclusion is there is something going on with my SD card?