Help! Buttons in button set disabled but still show as visited when clicked

I'm making a fun interactive lego building slide to take learners through a step-by-step process. I have 11 lego bricks I want them to click, in order, to go step by step. Each brick is a group of the lego image and a text box with a number. Because you can't make multiple groups into a button set, I made all of the lego images a button set. It seems like all of my triggers and animations are working okay, EXCEPT... even though I have each lego image in the button set starting with the initial state of disabled, and for them to stay disabled until a trigger on each step's layer changes the next step's lego image to normal when that layer timeline ends, the user is still able to click any group/lego image in the button set and have it show as visited. How is that happening if all of the lego images in the button set are starting as disabled?? (I tested to see if they were showing as disabled by changing the color of lego #2 to gray).

One more attempt to explain: If you view the slide, the gray lego block #2 is starting in the disabled state and should theoretically not be clickable, right? Not until the learner views the entirely of the step 1 layer and a trigger turns the lego block to normal when that layer's timeline ends. But as you can see, you can immediately click gray lego block #2, without viewing the step 1 layer, and it still changes to visited. I'm stumped. 

Am I missing a trigger here? Is what I'm trying to do not possible as it's built? Would really appreciate some help in getting this to work!