From the 4th Season, I noticed the writers forgot all about the dinner that was scheduled at the Stephen's home. This is the episode where Larry Tate is jealous when Darrin invites a client, Chase and his unseen wife, over for dinner.

So Tabitha twitches her toys to become life-size and Sam and Darrin think it's prudent to cancel the dinner. Of course, they are unable to call the Chases, but they reach the Tates (which prompts Larry to drive over and pick up the toy soldier at the Stephen's house in his drunken stupor). The rest of the show involves Darrin and Sam running after Larry. There is no other scene or mention of receiving or notifying the Chases that the dinner has been cancelled.

I just thought it was strange (unless my official DVD has an edited cut) that they didn't follow through to receive the Chases at their home.

Not really, Darrin got a hold of Louise before the Tate'e left and canceled with them, the client had already left, arrived after Larry and the toy solder had left with Darrin following them to the bar, then the client shows up at the Stephens house, Samantha still there makes their apologies and cancels, most likely vie the excuse of an illness in the family,client leaves probably hits a fancy restaurant and a show and Samantha lights out after Darrin.