Here's my complete trail of mouse click by mouse click JMP breadcrumbs I'm using to get the 20 run I optimal design with 5 replicates, RSM model. Since your model effects aren't in the same order as mine in the Model window I'm wondering if somehow the way in which you are entering effects in the model window is having some influence? I'm running JMP 14.2. Here goes:
From the JMP Home Window
1. DOE -> Custom Design.
2. Enter "4" as the number of factors in the Add N Factors window.
3. In the Add Factor drop down window, selecte continuous factors.
4. Click Continue.
5. In the Model window, click on the RSM button.
6. Enter "5" in the Number of Replicate Runs window.
7. Select the User Specified radio button in the Number of Runs window.
8. Enter "20" in the User Specified window.
9. Click on Make Design.
10. Click on Make Table.
Hopefully you'll have your 20 run I optimal design, with 5 replicates.