Background of the issue:
I am trying to access hidden link, but WPML redirects me to a 404 page. The original website is hidden link. I have created a test site hidden link. I have deactivated all plugins and changed the theme to default WordPress.
Symptoms:
WPML redirects me to a 404 page only when the GET variable is 'projects'. With any other variable name, everything works correctly.
Questions:
Why does WPML redirect to a 404 page when the GET variable is 'projects'?
How can I prevent WPML from redirecting to a 404 page with the 'projects' GET variable?
The second tier support also agrees that there might be a post type, taxonomy, or some element that had the projects slug and WPML had to manage those.
That is the reason of the problem. You will need to check the database of your website to find out what that might be.
The main issue here is that everything was working fine, and then, seemingly out of nowhere, WPML started conflicting with the post type slugs. Another confusing aspect was that WPML conflicted with a GET variable rather than a post slug.
I would have appreciated a bit more detail on the issue, such as where in the database I should look for the conflict or why WPML behaves this way.
That said, I have found a workaround, and my issue is now resolved.