I honestly don’t know. I am not aware of any WooCommerce field which stores the SKU without the dots. If you had some other custom field previously selected, then try that, but I don’t know your previous configuration unfortunately. The index table engine should be able to do that.
It’s a custom field called SKU (Woocommerce standard is _SKU) – i have both selected.
I already put it in the “index custom fields” – but still no luck.
Please follow the tutorial above, make sure to recreate the index completely after making changes, as well as selecting the index table engine on your search instance options.