I have been casting Enhanced Strength Enhanced Armor, and Surge of Strength and Surge of Armor, at the same time, and watching them stack, for as long as i can remember. Then i logged in on Sunday, and Surge of Armor no longer stacks.

I have always had these four spells on my hotbar, and I have been routinely casting them as my standard set of buffs, forever.

The Enhance buffs have been applying the same rules as the Surge line of buffs. The rules have always been that we cannot cast Surge or Enhance of Strength and Power, Dexterity, Focus, or Heath at the same time, for example. The only spell that is different has always been Armor. Even now, I can cast Enhance Armor and have it stack with Enhance Strength, just as i used to be able to cast the corresponding Surge spells and have them stack.