Flip Box Links don't work anymore

Hi, my links that I’ve set into my flip boxes suddenly don’t work anymore - in all of my portfolio posts. The links are set correct and always worked in the past. But what happens now: when I click now on the link in my flip box, always the links are getting doubled and I’m getting an 404 error. Even when I create a new flip box, I have the same problem: my links somehow get doubled. I also checked my permalink settings. Everything like before. Don’t know where the problem is. I appreciate your help!