I'm having a similar problem. I've tried tackling it several ways and seem kind of stuck.
Ideally, I want a limited-rotating turret to slowly move towards either 20-degrees left or right as long as either left or right arrow are held down.
My first attempt:
Turret.Angle = 270
On Left Arrow is down, Rotate Turret 5 degrees toward 250
On Right Arrow is down, Rotate Turret 5 degrees toward 290
In practice, what happens is as long as I hold left, the turret snaps to 265 (270-5) and stays there... so basically it's only updating that condition one tick when Left is pressed, rather than constantly while it's held down.
... I tried tackling it this way:
Turret.Vector = 0
Turret Angle = 270+Vector
On Left Arrow down, set Vector = -20
On Right Arrow down, set Vector = 20
Every Tick, rotate Turret 10 degrees toward Turret Angle (270+Vector)
Still no dice, it's rotating 10 degrees either direction only, so it's still updating only once. I just started using Construct 2 this week, so maybe there's something I'm missing about how to get this to update every tick?