Hope you're well today. 🙂
I've spoken with our engineers regarding this problem and we've been able to implement some changes to your site's back-end that should get this working for you. You should, hopefully, no longer be seeing this error message regarding your Web Stories.
Please do let us know if there are any further problems with this and we'll do what we can to assist further.
Otherwise, have a great rest of your day!
All the best,