Mobs attacking Wall of Frost when not behind it

Mobs will often attack the wall of frost when they are between me and the wall.

Sometimes they will actually run away from me to attack it.

Is this a bug or WAI?

Should the walls aggro mobs like that?

The frost wall is kind of OP right now anyway with Cascade and when used with
Comet+Seal so I wouldn't mind if mobs were a bit more intelligent about their target selection.