I noticed that importing related fields with Title and URL doesn’t work. 
I have my file with “Projects” that belong to Listings. In file I have a slug of listing that Project belongs to but wile importing it’s not going in the field. 

In import template I’m adding: https://superstolarz.dvlpr.pl/stolarze/{authorurl[1]}

Where  {authorurl[1]} is a slug. 

So when my slug is /3topmeble/ it goes into  https://superstolarz.dvlpr.pl/stolarze/3topmeble – which is as you can see working link on the site but still doesn’t go correctly