Woocommerce does hijack the main query on the shop page / product queries, so it’s possible that you’re used to referencing your custom fields within the loop or in some other context where the global $post is the page you are on, but in this case the contents of $post will be Woocommerce products and not the page.
If this is for your base shop page you can reference the custom fields like this (change for the meta_key of your custom meta box fields)
//returns shop page post object
$your_shop_page = get_post( wc_get_page_id( 'shop' ) );
//access your meta fields like this
$your_shop-page->your_meta_key;
I hope this helps in your situation, if you use the above code it would help to make sure you are on the shop page and those values exist before attempting to output them, always code defensively!