You need to shoot your product on AutoMask mode with a specific crop frame ratio (for example 1:1 square). After setting up the crop, parts of your machine can be seen inside the crop frame.
Then, when trying to adjust the AutoMask mask, the software cannot work properly.
The software doesn't work properly because it detects the parts of the studio. It is
preferable for the AutoMask that the background is completely homogeneous.
So, the best is to adjust the crop in the liveview so just your product is inside the frame. Then, to keep the ratio that you need, you will have to use the "Crop and Fill" feature.
To do so, click on
the "Crop settings" and under "Crop Ratio", select the "Free Form". Then, select "Ratio" under the "Crop and Fill" and choose your specific ratio, as well if you want to fill it with a color or to leave it transparant.
After, adjust the crop frame to your product so everything is cut out and you only have your product in the crop frame.