Hi Tom,
A client is using this plugin on their store and in our testing it appears to prevent a search query such as “?s=search&post_type=product” from working properly (where search = the search term”. Our goal is to use the Shop archive layout to display the store search results and it comes back with: “No products were found matching your selection.” Without the plugin activated the search works as expected.
Testing: SKU Generator for WooCommerce Pro v1.2.1 on WooCommerce 3.3.5 with WordPress 4.9.5
Could you have a look and see if it is something that could be patched.
Thanks!
Justin