Hello there, CPI-DGCM,

The Automatically build required subassemblies checkbox is enabled when you use another assembly item to build the product. See the sample screenshot below for your visual guide.

You can visit the Combine your inventory items to build finished goods to learn more about building a product.

If you have already set up the item and the checkbox is still greyed out, the data on your file may be damage. You can run the verify and rebuild utility to fix this.

Don't hesitate to post again if you need anything else while using the inventory assembly feature. I'm always around to help you.