Trouble with picking random instance

I have 3 towers on the screen. I'm trying to choose a random instance to spawn the arrow, but it will always spawn on the tower with the lowest z order rather than randomly. There's no additional code that would cause this. What am I doing wrong here?

I am not sure

I just made a new project with the same code but all works fine with me

Also when you said Z order is this a 3D game?

My guess, it first picked the first visible tower and because there is only one picked there is no random.

Try to put "pick a random Tower instance" on top and "Tower is visible" on bottom of this sub-event.

Moving "Tower is visible" has no effect. Even if I remove it completely, it makes no difference.

I am not sure

I just made a new project with the same code but all works fine with me

Also when you said Z order is this a 3D game?

No, it's not.

No, it's not.

So you meant lowest Y?

I was able to get it to work by adding an instance variable "picked" true/false, then checking against that to do the random picking.