No that doesn't matter. But only that timeline screenshot will not help. Could you answer my other questions? I see that the buttons start at the same time in the slide, do they overlap? Do they have a pause (you didn't show all of the timeline)?
There is a click box at the top of the stack: is this perhaps covering up some of the buttons, what is its goal?
The buttons have an advanced action, but do you not use an On Enter action to make the checkmarks visible based on what has already been visited? Can you post a screenshot of the advanced actions? Timeline will not help a lot here.
Lilybiri