Steps to reproduce:

1. Create the map, add some map element, save and export it
2. Change the Icons for this element, f.ex. instead of Default for Problem, Maintenance and Disabled, set any other one. Export map in a separate file
3. Perform two actions
   • Import first file, without icons. 
   • Change the icons to default. Import second file with icons changed.

Result:
After importing the file without icons - nothing will be changed. Map element will still have all the icons changed. If we return the icons to default and then will try to import second file - then icons will be updated. 
Expected:
Settings for the icons must be changed in a both cases during the import.