Long-time Insider Dev participant here. I verified my system meets every requirement, including TPM 2.0 & Secure Boot (both on) & DirectX 12. Yet both the health check tool and the Windows Insider Program settings say my PC does not meet the requirements.
The only possible discrepancy I found is DXDIAG shows my display driver is WDDM 3.0, and the requirements specify WDDM 2.x. I would think WDDM 2.x or later would suffice, but could that be the problem?