Custom Javascript or HTML Blocking Analytics?

Hi All, 

Has anyone run into any instances of custom javascript or html blocking website analytics?

I added a floating button to a few pages of my site with html+css, and I used javascript on two other pages to help turn a few code blocks into clickable boxes. A couple of days later my traffic dropped sharply as per Squarespace and Google Analytics. The click-rate on my ads during that same timeframe was higher than ever before, so I knew something was off. I removed all of the custom code and the analytics have recovered.

My ads all linked to this secondary landing page, which only had the floating button html added to header code.

Thanks!

Tyler