I'm using a mass import extension to import product URL Keys for a Magento 2.3.0 site which recently went live. The URL key information in the backend product detail is correctly updated but Magento continues to use a different URL key (this may have been the original key when the product was created or it may be magento default - I'm not certain). This is causing indexing problems, our generated sitemap shows the correct URL, i.e. it uses the backend URL key, but that URL is ignored by Magento, is unavailable and hence we're getting soft 404 errors from search engines.
I can force the URL key to correctly update by adding the product to our 'main website' again in the backend either from product detail or by using a mass action. This isn't a practical solution when we have over 50K products in our catalogue. It takes about 4 minutes to update 200 products this way and there are often errors (URL key already exists).
My question is where in the DB is the URL key actually stored? Is it possible to force the database to 'see' the updated URL key using SQL?