Passkey fails only on developer.apple.com

I've got a weird issue where Passkey fails, but only on developer.apple.com.

Here's how it manifests:

• On portal, select "Sign In With Passkey"
• Get prompted with TouchId (on my MacBook)
• Portal says "can't verify your account"

However:

• Sign in with Password works fine
• Sign in with Passkey on any other website works fine

Not sure if it's related, but this appears to have happened around the time I had my logic board replaced. I did have weird issues with my iCloud account where I had to sign out of all devices, then sign back in. I assume this has to do with the hardware having the same serial number, but somehow appeared like a different computer in other ways.

Things I've tried:

• In Passwords app, searching for "apple.com", I only see passwords, no passkeys. However, Safari password auto-fill always suggests the passkey entry first.
• developer.apple.com does not appear to have any way of managing sign-in credentials
• accounts.apple.com does not appear to be any way to manage passkeys.
• Sign in with Passkey on iPhone also results in "can't verify your account".
• Called AppleCare support, they were unable to help. Since Passkeys work for other websites, they believe this is a problem specifically with developer.apple.com. They suggested calling Developer support.
• Called Developer support, they were unable to help. They said AppleCare Support is best suited.
• Filled out Feedback (FB1818****)
• Posted on Developer Forums. Since this is a user-level issue, they suggested posting here.

System:

• macOS 15.6
• Safari 18.6

Has anyone else encountered anything weird like this? Is there any way to fix this? It would be nice if I could just delete the old passkey and create a new one. But I can't find any tool that will let me do that.

[Edited by Moderator]