Im having the same issues (panic) as you.
I sell "generic’ products designed and manufactured by me (posters and prints) within the Home and Kitchen category.
I currently have around 50 or so listings that I set up over two years ago to test the water on amazon with. Today decided to expand my listing quantity and applied for the exemption within the required category which was granted immediately. As soon as I began the listing process the page jumped and I received the same message as you.
I decided to try the chat help and was informed that Amazon no longer allow the creation of new listings in my category. He could provide no notification statements proving this and I really think he was talking rubbish as I cant imagine for one moment that Amazon will not allow the sale of posters and prints!
Hopefully it is a bug otherwise my Amazon business is finished before ive started!