One you sign in and navigate the store, you are instantly signed out, signing back in just recreates the issue. Some pages require you to be signed in before it shows and when customers click join the button it just asks them to sign in
Below is an example (not my store) attached video clip showing exactly what happens:
Any reason why this could be happening, and a way to resolve it?
@tcinfo I figured out it was a bug caused by a code from an app I installed. You can check this out by disabling your apps one by one and checking if the problem gets fixed. Once you notice the app that causes the problem, you can either try to locate the bug, contact the app to locate and remove it or contact a shopify expert to locate and remove it.