Mantra of Destruction and Acolyte of Chayula's Lucid Dreaming node bug

There are several issues with Flames of Chayula but it's hard tell which are intentional design decisions and which are bugs.

An issue that seems like an obvious bug to me is that the purple flames granted by the Mantra of Destruction skill do not have their duration doubled by the Acolyte of Chayula's Lucid Dreaming ascendancy node. They do have their effect doubled, however. It would be really strange if this inconsistency was intentional.