could it be that it's only related to the p4 then?
they forgot the J version didn't have a model with sandbags
I guess that command panzer IV that is on the first screenshot still uses old model and it should get it's sandbags if it was the case.
Well I know something about panzers me too. I dont' know for sure if a model i existed, but clearly it's not a "G" late or no late model, nor an "H" because of the reasons you point it out. The gun cache (top) it's same as ausf j model, but the turret seems to be a little different. So it's not a J model either. So, if it's not an i (??) model, I don't know what it is... Maybe Pz IV ausf. RELIC. A new Panzer IV type.
I'm not sure but for me it's just model H with schurzen ripped of until vet 2. They probably model it as H from the beginning but wanted to visualize that it "gets" more armour.