It appears on the USA area:
Are you seeing this problem on the World Map as well as the North america zoom map?
it's maybe due to a bug in the geo location database, returning wrong lat/long for a Hong Kong visitor... but if you see this bug only in the zoomed map, and not on world map, it's likely a bug in Piwik map algorithm. Thanks for sending more info
It appeared on the World Map as well as on the zoomed part. Then you're saying it's independent of Piwik's algorithms?
I think it's independant of Piwik algorithm. To be sure, you can look at browser > Developer Tools > and check the response from the Live API. it contains all visitor info, including the latitude and longitude. Check whether the lat and longitude for this visitor is indeed in the USA or whether it was supposed to be in asia. I assume it works well, and it's a problem with the geo location DB, so closing issue, but I may be wrong, so feel free to reopen!
OK, sure, thanks for the response!