Logout not working

My logout page has stopped working.

What did you before it stopped?

I had a logout page (with nothing in it) which was logging out. I suppose it was referenced somewhere in WordPress or my membership plugin (usersWP), but I’m not sure where that would be. I contacted the membership plugin support who said it was more likely a WordPress issue. When it stopped working I used this https://www.wpbeginner.com/wp-tutorials/how-to-add-the-wordpress-logout-link-to-navigation-menu/ to add a logout page with URL https://example.com/wp-login.php?action=logout which isn’t working either.

Any help would be much appreciated because I’m really stuck!