Well zooming in and out doesn’t really make a difference. The map stays incomplete, which is especially visible with the river. Also the roads are drawn with very pale edges, but maybe that’s intentional or a different issue.
Firebug initially shows lots of successful GET requests, also a single “Error: data.oauth is undefined” error apparently from Google Analytics. After zooming in and out a few times some network errors appear, like this one: “NetworkError: 403 Forbidden - https://d2munx5tg0hw47.cloudfront.net/tiles/15/17187/10664.mapbox”. But the map is already displayed broken before these errors appear.
I guess I’ll wait if a new release of Firefox or Mapbox fixes this
It would be nice though if I could opt-out of the WebGL map. Switching off WebGL in Firefox fixes the map issue, but also downgrades the photo viewer.