My 1099b has a blank box 1e (cost basis). I hit "My 1e is incorrect or missing" but when I submit it takes me back to that section and says "need info." What do I put?

After clicking "My 1e is incorrect or missing," it takes you to a page where you can put it in yourself as an amendment, but it's still forcing me to put something in the original box despite me saying it's missing. I don't know what to put.