Mashable said it's because users were reporting innacuracies for their own locations, and Raw Story doesn't have any metrics to support their claim... as usual. I couldn't find anything on the number of maga accounts from other countries.
Not to say astroturfing isn't happening, there's foreign interference for sure and some of those screenshots are probably legit. It's just more likely that Xitter's broken and their new feature didn't work.