To replicate the bug:
1) ensure that in the properties of the "Local network" map Host Group label type is set to "Element name";
1) open "Local network" map in map editor;
2) add an icon;
3) set in the icon properties: type - host group, select a group, press Apply button.

Map becomes corrupted - only icons are shown on the screen.
The same error happens with any icon type except Image.