This has just started occurring for our dev site (localhost) this afternoon. Every page that has a request to the graphQL api throws a cors error and doesnt load the page content.
Ive tried following a few of the other guides on here to fix the issue but so far none have worked. When i click through the error i get a 'Prismic-Ref missing from header' message - however, i can see the prismic-ref: in the request headers
From what i can tell this is/was also being looked at here - Request header field prismic-ref is not allowed by Access-Control-Allow-Headers in preflight response - #16 by sbaughman - it looks to be fairly intermittent so im not sure if a permanent fix has been implemented yet, any updates or help from the prismic team would be much appreciated