What to do if your links work only sometimes
If your site only works after refreshing a page, it's most likely because AJAX is enabled. Here's how to disable AJAX in Duda and Squarespace.
The Memberstack script could also be taking a while to load. We'll need to look into this for you, so please let us know if you think this is your issue.
What to do if your links never work
Confirm the header script has been installed.
Make sure you're using the correct link or data attribute.
Check your browser/version. Memberstack doesn't work in some legacy browsers (e.g. IE 6 and below).