I had the same thing occur to me when using V4's expression morphs with my custom morphs, they all look distorted even when smiling.  I cringe using the built-in expression morphs themselves.  I never knew you can correct it with the morph tool.  I had to use it to smooth out the distortions just through her gumline.

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Asus N50-600 - Intel Core i5-8400 CPU @ 2.80GHz · Windows 10 Home/11 upgrade 64-bit · 16GB DDR4 RAM · 1TB SSD and 1TB HDD; Graphics: NVIDIA Geforce GTX 1060 - 6GB GDDR5 VRAM; Software: Poser Pro 11x