Instant logout on iCloud.com mail. Error: Missing X-APPLE-WEBAUTH-TOKEN cookie

Other apple sites work fine.

I login to icloud.com successfully. I click on the mail preview to bring up the mail portion of the site.

Once I click on any email to read, I get "Missing X-APPLE-WEBAUTH-TOKEN cookie".

This has been going on for at least a week.

I use Chrome because I'm mostly in the Google ecosystem.

Latest Chrome on Sonoma 14.6.1.

Reboots, deleting cookies/data, disk util repair, other browsers, etc... Nothing helps.

And if it does, it only lasts a few minutes until I'm logged out again.

This is on a M3 Pro.

Any ideas?