Hi recruit_tatsuya,
According to this thread your problem was solved by using 5.5 instead.
Does the problem still occur in 5.6 or does Sophia’s advice work there as well? It would be great if you could check and submit a bug report in case it is still broken.
In my environment I solved it by using Unity 5.5.1.
However, since Unity 5.6 beta 8 did not solve the problem, I reported here.
Sorry, I can not try it with the latest version.