Hey folks - the August 31 Polaris CDN 1.1 release candidate includes a Select fix for “an empty value showing before the options parse”: Polaris CDN 1.1 release candidate - Shopify developer changelog
You can test this change by loading https://cdn.shopify.com/shopifycloud/polaris-1.1-rc.js. If you test this build and can confirm whether the issue still occurs, please let us know!
This release also introduces semantic versioning for the Polaris CDN, including stable, pinned, and release-candidate channels. More details are available here: The Polaris CDN is adopting semantic versioning - Shopify developer changelog
Hope this helps!
cc: @Alex_Moser who asked about this recently as well: Blank s-select element