When including Ped Load in addition to HL-93, I'm getting same rating for inventory and operating. Local Buckling under strength is controlling the rating, but it is giving the same rating result for inventory and operating rating even though the live load factors are different. I do not have this issue if I don't include pedestrian loading. Under the analysis tab, the moment diagrams for both HL-93 and ped load seem correct, it's just when combined in the rating things are off.
It is possible that there is an error in the way the combination of pedestrian loading and HL-93 live loads is being applied in the rating calculation. You may want to double-check the input data and the rating methodology to ensure that the combination of loads is being correctly considered. It may also be helpful to consult with a structural engineer or the software provider for further guidance.