Spells: Largarn's Lamentation and mezzes

[Tecmos Deception]

Are mez spells supposed to be blocked from landing on NPCs they normally would land on because of the debuff from LL?

Llewellyn was talking about dying to a mob another enchanter had been casting on after the guy gated and then the mob was immune to Llewellyn's mesmerization and dazzle spells. So I ran through the oddball enchanter spells and found that if I cast LL on an NPC it would be stunned for several seconds, but then a couple ticks later I would get a "your spell has worn off" message. So it sounds like it is working like the whirl line. But the thing is, that debuff from LL stops mezzes from landing until it wears off. I tested whirl and dyn's also but mezzes stuck fine with those spells.

Intended?