City wall isn't stopping robber
When I put up city walls and the robber is placed on my hex, I still lose resources when my number is rolled. I have a physical copy of the game and in the rules it says that city walls allow your city to produce even when the robber is on its hex
What wording are you talking about? I just reread the rules from the manual about city walls and all I see there is "Each City Wall you control increases the maximum number of cards you safely hold in your hand when a "7" is rolled on the production dice. Each city wall add 2 cards to this limit."
Yes StanCason is correct. You're interpreting the rules incorrectly. City walls only increase the amount of cards you can hold without the robber making you dump half of them (2 per wall)