I cannot use VisemeDriver Component

AreVisemesValid is updated inside the Update function in OVRFaceExpressions.cs at line 213.
It is computed as the logical AND of the following two conditions:

• OVRPlugin.GetFaceVisemesState(OVRPlugin.Step.Render, ref _currentFaceVisemesState) == OVRPlugin.Result.Success
• _currentFaceVisemesState.IsValid

The first function, OVRPlugin.GetFaceVisemesState, is defined in OVRPlugin.cs at line 10308.
Inside it, the following call at line 10315 returns Failure_Unsupported:

Result res = OVRP_1_104_0.ovrp_GetFaceVisemesState( stepId, -1 /* OVRP_CURRENT_FRAMEINDEX */, out cachedFaceVisemesState );

Because this call returns Failure_Unsupported, AreVisemesValid always becomes false.

Since OVRP_1_104_0.ovrp_GetFaceVisemesState is implemented inside a DLL, I cannot inspect its internal implementation.

Although the Meta Movement SDK claims to support visemes, the current situation is that they cannot actually be used. This appears to require a fix. I am looking for an alternative approach.

Please help.