RC, I think your dealer just did not get allocations for this year. The first GTR's have arrived to dealers, of course these examples are sold out already. Some cars I've spotted by browsing Instagram for a couple of minutes,

Black in Switzerland:  https://www.instagram.com/garagegut/

Silver in Germany:  https://www.instagram.com/p/BSJ-TTuDtUj/?taken-by=schoenlecker

White and green in Poland:  https://www.instagram.com/p/BSE4uZSAIdv/

Black in Poland:  https://www.instagram.com/p/BSIxfGwgEIJ/?taken-by=amg_na_maksia

Red one from a racing driver (think it's AMG's car, not a customer car):  https://www.instagram.com/p/BOmStI5B7jV/

And there are multiple pictures everywhere of green and magno grey ones, mostly without plates or with Stuttgart plates, those I have not counted above, think they are just demo cars. However, first green one has been spotted without Stuttgart plates, so perhaps that's a private car alrea:  https://www.autogespot.com/mercedes-amg-gt-r-1/2017/03/16