A number of bugs have now been fixed and a new updated Map Editor version is available for download.
Map Editor 11.21.11.28 Release notes
1. A bug prevented maps, exported from WAsP, from being opened by the Map Editor, if these maps contained very long polylines.
This bug has been fixed.
2. The projection system has until now operated with UTM, UTM-N and UTM-S projections, although UTM and UTM-N were functionally identical. With a new GeoProjectionDatabase (no. 17) the "plain" UTM has now been removed from the projection system, but when opening old maps, "plain" UTM is automatically converted to UTM-N.
The above also applies to projection handling in WAsP and in the projection transformer utility.