The first button selected (not a Submit/Quiz button) requires TWO clicks to register click...

I have two slides in a course and each have multiple "buttons" that are required to be clicked prior to moving on to the next slide. In both cases, the buttons are not Submit buttons or quiz buttons. They are standard buttons that reveal additional information through animation. 

In either slide, when I click the first button, it requires me to click it twice to initiate the animation. The remaining buttons on each slide only require one click. This is true regardless of which order I click the buttons on each slide. So, on slide A that has 4 buttons, if I click the the button on the far left first, it requires two clicks. The next three only require one. If I decided to click the button on the far right first, then that one requires two clicks. The remaining only require one. This started happening on both of my button slides at the same time. I may have selected something inadvertently but can't seem to figure it out. Any help is appreciated. Thanks.