From the screen capture, I see that you are reviewing results from Design Pass 0. This pass does not include user reinforcement, which is why the number of existing bars is shown as 0. Pass 0 was created solely for the purpose of span detailing. When extending reinforcement according to the span detailing rules, we did not want to an excessive amount of user defined reinforcement to create excessive span detailing requirements over the entire span. The Pass 0 design is meant to represent the minimum reinforcement at the cross section, which is then span detailed according to the selected design code provisions.
In Pass 1, the Pass 0 reinforcement is not considered. However, the design considers the user reinforcement and adds supplemental reinforcement as required. Pass 2, used primarily for shear and ductility design, uses the cumulative rebar designed in Pass 0 and Pass 1. The Final Pass is meant to calculate the capacity based upon the final quantity of reinforcement. This pass includes user reinforcement and any program reinforcement designed in Pass 1 or 2, but not less than the reinforcement designed in Pass 0. The Pass 0 and Pass 1/Pass 2 results, then, are enveloped but not summed.