My answer is correct
Why this answer is not accepted as correct?
Cô ấy mua trái cây hàng chiều.
It is not a sentence that anyone would say, so VNese team excluded that from the list of correct answers. There is nothing wrong with that, however.
Thank you for you reply. Does it mean that the sentence is just not natural or too formal?
Neither, I think it is preference.
Is this showing up as a fill-in-the-blank for anybody else? I've never seen that on Duolingo before
Yeah I think it is a new feature