My name is Lilith, I'm on the Social Care team at Shopify.
I'd be more than happy to help you out with this.
I went over to the product page that you linked in your post. It looks like the product is able to add to cart. I have a quick recording I took to show you what it looks like for me:
Would you happen to have a screenshot or some extra details from your Product page in your Admin? I'd like to check to see if it might be a localized issue.
If you're finding some trouble updating your pages on your site when you're on the customer-facing pages, I would recommend doing a cache clear as well to make sure that the most up to date version of your website page loads up on your browser. These instructions here can help you clear your cache depending on the browser and device you're using.
Let me know how you do with the information above! I'm happy to answer any questions you think of as you work on your business.
@vperkovic, that's fantastic! Great job in the fix and getting that done so quickly.
Did you have a custom code or app that was interfering in your theme.liquid at the time? This might help other business owners with a similar situation in the future to know.
Keep us posted if you need help anytime! Thanks for letting me know you got it fixed.