JS doesn't run in Shopify section

I'm having a hard time figuring this out. I've added the following JavaScript inline to a Shopify section:

let hash = window.location.hash;
let tab = document.querySelector(hash + " + div #tab-" + urlParams.tab);
tab.checked = true;

What it does: switches between accordion tabs based on a URL parameter. The accordion tabs were built using checkboxes and styled with CSS according to the "checked" item. Three things:

1. It works as intended in the dev console but not when loading the page.
2. Checking el.checked on each of the tabs reveals that the correct one is checked after page load (the others are false).
3. The console can log on page load from my script.

Is there maybe something weird that Shopify does? I don't have a ton of Shopify experience.