When I created the XY coordinates for the face and the mouth, and then performed automatic generation for the four corners, only the mouth was misaligned (see the first image).
After researching various solutions, I tried generating with all blendshape values set to 0, as suggested by others with the same issue. While this allowed automatic generation to proceed, the mouth shape became severely distorted, requiring extensive manual correction (see the second image).
When I attempted to fix the distortion in the second image using blendshapes, the weights did not reflect properly, causing the front view to become distorted again. Re-setting the weights resulted in the same issue (distortion of the front view).
Consequently, even if automatic generation succeeds, it is impossible to correct the result.
The root cause of the issue — “only the mouth is misaligned when performing automatic generation for the four corners” — remains unknown.
Because of this, I have had to redo the mouth modeling three times. Each time, the automatic generation caused misalignment, or even if it succeeded, the mouth shape was severely distorted, making it impossible to proceed with the mouth modeling.
I would appreciate a quick solution. If anyone knows how to resolve this, please let me know.

