Ensuring devices meet organizational security and compliance policies
If Windows Defender is installed, active, and fully updated, but Intune still reports the Antivirus compliance setting as non-compliant, I'd recommend checking the device's compliance details and syncing it again (which can take some time).
Also review the Windows Security Center status locally to confirm Defender is correctly registering its health state. If multiple devices are affected, it's likely related to the current reporting issue rather than an actual antivirus problem.