I too am using WooCommerce 4.7.0
Here is an update on the issue, I have done some more troubleshooting.
I erased the parent SKU from the products of mine that have the variants.
Some orders now coming in with “blank”, still pulling from the parent SKU field rather than defaulting to the variant sku.
Some orders still show the customer selected attributes (size, color) in the drop down – on shipstation, for example. but other orders it is blank and so I still have to guess the color.
Is this a version update issue or something else? Now I have to change some SKU’s back to at least differentiate product TYPE when fulfilling orders…