Sticky Header Not Working

Currently building a site with Astra and the Astra Pro addons. Sticky Header is not working at all. I’ve watched several tutorial videos and have checked the appropriate boxes in Customize, to no avail.

I previously tried two free plugins to create a sticky header, and when neither of them recognized any of the classes or IDs I pulled from the header (including #masthead), I went ahead and got the Pro addons and deactivated the other sticky header plugins.

Any assistance is appreciated.

For reference, I’m drafting up several pages with Free Elementor and use the Insert Header and Footer plugin for GTM code. I don’t think any other plugins I have would interfere with sticky header.

The page I need help with: [log in to see the link]