Compliance Policies - Device Health Attestation failing (Syncml 404 / 0x87d10194)

Windows 11 devices are non compliant in Intune against BitLocker, Secure Boot and Code Integrity, all three returning the Syncml 404 error. The settings are genuinely enabled. The real cause is the device can't retrieve a Device Health Attestation certificate, so the health cert status sits at 65535 and the retrieval task fails.

What I've found: the TPM is healthy (present, ready, attestation capable, firmware not vulnerable), and the endorsement key cert is valid, chaining to Nuvoton TPM Root CA 2111. But the EK chain check comes back invalid with zero intermediate certificates, because the Nuvoton key is signed straight off the root with no intermediate for the chain walk. A Hyper-V VM on the same build and tenant works fine, but only because it has no manufacturer EK cert, so it skips that chain check entirely.

What I've tried: patching TPM firmware (ruled out the older ADV190024 issue), refreshing the local trusted TPM certificate store, and rerunning the retrieval task. None fixed it. This matches Rudy Ooms' well known call4cloud writeup, where he concluded it's a service side trust problem that can't be fixed from the device.

It's now appearing on brand new Dell hardware too, so I can't just exclude the old kit and move on.

Is this a known issue with the Nuvoton root chain, and is there a supported fix or position from Microsoft? Screenshots below showing the compliance errors and the failure.