You possibly were having a similar issue as this user: Lights turning on/off on their own - #27 by roblenderman
What it sounds like is they possibly had the away lighting enabled and then when Amazon changed the "Guard" feature it got stuck on with no way to shut it off. There is a thread on the Amazon forums with a bunch of people who had this issue (link in that thread somewhere).
One of the supposed fixes is to remove the device from Alexa totally, and then add them back. Which you would have done by switching it over to the Hue skill.
