When using a wrench on the mechanical mixer you should see an overlay, indicating the mininum number of ingredients, and you should able to change it with the mouse scrolling wheel.
This overlay does not appear. And I'm not able to change the ingredients number.
On older versions (1.15.2) this feature was working.
With 1.16.4 it is not.

The overlay that let you change the minimum number of ingredients was removed in 0.3 in exchange for the recipe filter on the basin.