Description:

I have observed a reproducible issue with MMD facial expressions in VRChat:

Avatars created in a project in February 2025 function correctly in MMD worlds, with facial expressions working as expected.

When creating a new avatar in the same project, MMD expressions break.

Creating a completely new avatar in a new project also results in broken expressions.

Environment:

Latest Modular Avatar (MA) version

Latest VRChat SDK

No unofficial MMD extensions installed

Observations:

The issue seems related to certain settings present in older avatars—such as Animator layers, BlendShape mappings, or Face Mesh references—that are not automatically applied to new avatars.

This difference causes new avatars to fail in MMD worlds while older avatars continue to work correctly.

Steps to Reproduce:

Open the February 2025 project and upload the old avatar → expressions work correctly.

Duplicate or create a new avatar in the same project → expressions break in MMD worlds.

Create a new project, import MA and SDK, create a new avatar → expressions break.

Expected Behavior:

Facial expressions should work consistently in MMD worlds for both old and new avatars.

Additional Notes:

This appears independent of the project or Unity version; the problem persists even in a clean project with only official MA and SDK.

It may indicate a regression or missing migration in MA/SDK affecting new avatars.

Request:

Confirmation if this is a known issue.

Guidance on how to make new avatars compatible with MMD worlds without manually copying all settings from older avatars.