Stefan, thank the Mkgmap community who are doing their best to understand and reverse-engineer the Garmin map format. A really smart bunch.

The change between 17 July and 5 August is probably an upgrade to the latest Mkgmap version (r2008).

Would it be possible for you to do some research into the latest version of Mkgmap that is still working for you? I really don’t have the time available right now (nor the coming weeks). I’m fully immersed in some structural changes to the website and trying to provide feedback to Ligfietser and Beddhist which, I shamefully must admit, is really lacking.