My best guess based on what you posted is that the power factor is so skewed that there just isn't enough power left to run the machine. It's possible that the voltage and current are so out of phase that the effective available power is very low.
Also check the leg to leg voltage, as well as the current on each leg on both sides of the 45KVA transformer when running. Best guess is that they are way out of balance. 5% or so imbalance is normally acceptable.
So I think both the RPC manufacturer and Haas are both right and wrong.
It would be interesting to put a scope on the legs and look at the current and voltage waveforms.
Additional capacitors or inductors might be needed to correct this.