Power stones

I want to transcend my sword but it keep on saying "not enough souls to proceed" are souls also required?? Because it is not indicated in the requirement only 6 power stones...any idea?

Wow

It's was in update announces from Nanoo. Dunno why they do this and hide soul req on upgrade window. I hear that treasure upgrades need both read (30 power gems and 100 souls), but souls req not shown