Board Thread:Naruto Discussions/@comment-25192437-20150109095203/@comment-25192437-20150110073456

BeyondRed wrote: The Six Paths Sage Mode and Six Paths Yang Power were separate gifts from Hagoromo, the latter being a temporary gift. The "Yang Power" was simply a name for the seal on his hand, which as you said activated the Six Paths Chibaku Tensei and then returned to Hagoromo. It may or may not also be responsible for Naruto's ability to heal others with Yin—Yang Release, seeing as he always used his right hand to do so and never used it after losing the seal. But as far as we know, it has no direct connection with the Six Paths Sage Mode, since Naruto kept it after losing the seal.

If Naruto still had Six Paths Sage Mode, then I suppose the question becomes why didn't he use it in his battle against Toneri?