hi man!
as you see, I am from Paraguay. also use the map of Mapping plus one apart from Paraguay who manage locally that is more complete than the draft map and pass it to a USB flash drive to generate the map .. me finally goes with the name gmapsupp.img (lowercase) and and pass it to uppercase also to try.
I put the code in country_codes_generated is this:

{"gmapsupp.img":"AR,LA,BR,PY"}
my map i rename: gmapsupp.img

i trie GMAPSUPP.img and change in contry codes but nothing..