Don’t do webdev work in your personal browser account Opening dev sites in your primary browser/account is problematic. Opening in Private (FireFox) or Incognito (Chrome) is a must, since it usually turns off caching and removes you from any left-over accounts that might be interfering with your validation. I’ve always done dev sites in my dev browser, so good to hear a group that recognized (sort of) this: https://polypane.app/blog/always-open-localhost-in-your-development-browser/ And disclaimer: Polypane who wrote the article is a paid browser (after 2 weeks).