I might "recover" this problem, althought I don't know why.
Only in japaness web page, you can find firmware of old version (But Its gone now....). When flesh back to old version , seems could solve this problem.here
I've had more of a play, and it seems that it is an issue with one of my M5Stick devices, the YUN works fine with others. I'd still like to know what is wrong though, the device that is not working is brand new.