Yes, the person who did this lesson appears unaware of this basic form. I get so many wrong for what appears to be pedantry - worse, incorrect pedantry. It's extremely frustrating because it's a terrible idea to force feed yourself English sentences that are actively worse translations than the obvious - it's literally antipractice.
Practice doesn't make perfect, it makes permanent.
"There are groceries in the bag" fits better because the information the sentence introduces is the presence of the groceries - which is why "продукты" is at the end of the sentence. In the sentence "The groceries are in the bag", you are telling the listener the location of the groceries - the location is the new information - so it would go at the end of the sentence in Russian.