I'm sorry that MCStacker is not working for you. One of the main reasons why MCStacker does not work for some people is because the advertisements that show on the page sometimes interfere with the JavaScript code that runs MCStacker. Ideally I could remove all ads, but the site still relies on advertising revenue. This issue only affects a small number of users and the problem is usually temporary.
There are two ways you can use MCStacker Ad-free and more reliably. You could become a Patreon Supporter or you could buy the Deluxe Edition. Both of these methods should solve this problem. I understand that supporting the site in this way is not an option for some people and that's okay. I really want you to be able to use the site. To help you with this, I'm happy to give you this special link that sets a cookie in your browser which stops all advertising code from being loaded into any page on mcstacker.net for the next 24 hours.
I hope this works for you. If you try this link and MCStacker still doesn't work, it could have something to do with add-ons, plugins or browser extensions. Try an alternative browser to see if it helps. You can also try asking for assistance on the MCStacker Discord Server.