I’m having the same issue. I’ve found that adding the trailing slash makes the redirect work. So “website.com/redirect/” works but “website.com/redirect” does not.
I can’t expect my users to remember to add the trailing slash, nor do I want them to have to type it. The plugin always adds a trailing slash when you create a new redirect. I’m not sure if there’s a way to force it to omit the trailing slash. Or if there is, if it would solve the problem.