The recommended response surface model is called the Scheffé polynomial (Scheffé 1958). See the discussion of Cox Mixtures and the Scheffé Cubic macro in the Fitting Linear Models book. The Scheffé polynomial model does the following:
1.

Choose DOE > Mixture Design and make the design data table. To fit a model, the Y column in the data table must contain values. Either assign responses or select Simulate Responses from the red triangle menu before you click Make Table.

2.

The design data table stores the model in the data table as a table property. This table property is a JSL script called Model, located in the left panel of the table.

3.

Rightclick the model and select Run Script to open the Fit Model launch window, which is automatically filled with the saved model.

4.

Click Run on the Fit Model window.

The hiddenintercept property also causes the R2 to be reported with respect to the intercept model rather than reported as missing.
When there are effects marked as response surface effects “&RS,” JMP creates additional reports that analyze the fitted response surface. These reports were originally designed for full response surfaces, not mixture models. However, JMP might encounter a nointercept model and find a hidden intercept with linear response surface terms, but no square terms. Then it folds its calculations, collapsing on the last response surface term to calculate critical values for the optimum. This can be done for any combination that yields a constant and involves the last response surface term.