Problems calling "WiFi.disconnect()"


I'm currently using UNO rev3 with official wifi shield, everything just works fine (scan networks, connect, send data...), but when I try to disconnect from current network using WiFi.disconnect() the green led (labeled as "link") from the wifi shield turns off just a second, then the red led (labeled as "error") turns on just a second too.

After that the "error" tunrs off, and the wifi seems to reconnect automatically (led "link" turns on). I've done some research and some people are experiencing this problem too, it seems like a bug, but I don't know if its from hardware or software (from wifi library), I just cant "disconnect" and thats a problem. Anyone knows something about that?

Thank you so much, and sorry formy bad english