Hi matt
not being able to see live data on cranking may be a problem but first what voltage is the signal from the rps actually displaying on cranking? If it only rises slightly try disconnecting the return line and make sure you don't see any fuel coming out as you carnt build up pressure if the system is not sealed don't no if this will help you at all just what I would possibly do before taking a car back to the workshop.
Regards
Carl