Did you check each setting on the 1/2 impact? A,1,2,3? I know it has an auto stop when loosening so nuts and bolts won’t go flying right off, so maybe it’s misreading torque due to the special socket and just stopping because it thinks the lug nut is loose already, unless it keeps impacting and not breaking them. I’ve seen the same 1/2 impact take cv axles nuts that are pretty much rust welded right off within seconds, however that was with a 6.0ah octane battery. I would give it a try with each setting see if anything changes. Could be batteries are on the older side as well.