For a power bank to be able to charge a notebook, it must be capable of power delivery. It must also be able to supply the volts and amps required by the notebook. The Surface Pro, for example, needs a 44 watt power supply solution, but this powerbank can only deliver 45 watts. It is quite possible that this is another reason why it is not enough. The difference between what is needed and what can be called up could be too small to really be able to do this reliably. A model with 65 watts would certainly be more optimal, as you have more reserve.