One thing that hasn't been mentioned is the IBU formula being used. I'm not familiar with Beersmith, but in ProMash, I can select from 3 different IBU prediction formulas. I can tell you from experience, that the Tinseth formula tends to produce a more bittered beer than what will be produced when the Rager formula is used. I've studied the formulas intensely and find that the Tinseth formula does produce the most accurate correlation between prediction and measurement, but I still use Rager because I like how it affects my beers. Another reason to use Rager is because many older recipes used that formula.
With regard to chloride/sulfate ratio, don't rely on it to explain bittering or the lack of it. The ratio is nearly useless.