So, having two timelines in the same .layout file for a single event seems to cause a weird interaction.
For the Vanq's Steel Dance skill (essentially a Flame Aura clone), the looping layout on the EVENT_TRIGGER became bugged after Twinkle added a non-looping timeline next to the looping one to implement his glorious particles.
Something about having the two timelines does not work with some element of this skill setup. I suspect it overrides the looping layout's loop setting (making it not loop).
Separating the two timelines into different EVENTS fixed the problem. This is, of course, what the vanilla skill Immolation Aura does.
Just a heads up.