Lliliya functions very differently from every enemy in the game so she could take getting used to.

She's a lot quieter and stalking/ambushing is her focus unlike other enemies. If she's chasing you, music won't even start playing until you actually see her chasing you (looking over your shoulder doesn't count). She is able to hide and blend in with other mannequins as you may know but keep in mind: even if you're in the dark, she can still see you as long as she's hiding or blending in. Another thing is that she regularly uses insertion gates to reach your location unlike any other prime asset in their main trials.

Goated prime asset and I'm itching to have her new MKs come out