Topics fetch API always showing ();p=P0000000000000000000000000000000 as sec-browsing-topics header

[doctafaustus]

After following the demo instructions on https://topics-fetch-demo.glitch.me/, the fetch calls on the 4 topics sites are always showing ();p=P0000000000000000000000000000000 as the Sec-Browsing-Topics header value.

I've followed the demo's setup and troubleshooting:

• Chrome launched via command lined w/ the specified feature flags
• Enabled chrome://flags/#privacy-sandbox-enrollment-overrides and added all the listed glitch.me subdomains
• chrome://flags/#privacy-sandbox-ads-apis is disabled
• No adblocker or incognito mode
• "Allow all cookies" enabled