When I start the plugin there are two things I have to do each time: click the clay rendering button twice and checking and unchecking the "use base geometries" button.
When I start the plugin it seems defaulted to clay rendering mode. When you click the clay rendering button the render seems to restart and the button indication changes. But it's still rendering clay. So I click it once more and then it actually loads the materials.
Also the rendering always defaults to rendering in base resolution, even if you unchecked it in the past! So you have to click the button and unclick it to trick the system into doing what you want.