Most likely the top basket is not going back in correctly, think from memory there’s 2 positions for basket level. If you have a look you’ll know what I mean, if it’s not seated correctly water won’t go in to top spray arm & no wash from top.
Thanks Seamy, I suspected something like that, not sure if this model has a double height upper basket with small flap valves at the back where the tube from the spray arm locks on.