Maybe a scaling translation error. A result of Poser's absurdly small scale. I think that it's a vertex position rounding error that becomes obvious at such small scales. You encounter the same problem in pre GoZ versions of Zbrush and in Wings3d. Barring a "Go" utility or colorcurvature's PML I know a fix that involves a bit of subtractive morphing. An easy fix for just a couple of morphs, tedious when creating hundreds. I'll post a workflow if you don't find a solution.

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W10 Pro, HP Envy X360 Laptop, Intel Core i7-10510U, NVIDIA GeForce MX250, Intel UHD, 16 GB DDR4-2400 SDRAM, 1 TB PCIe NVMe M.2 SSD

Mudbox 2022, Adobe PS CC, Poser Pro 11.3, Blender 2.9, Wings3D 2.2.5

My Freestuff and Gallery at ShareCG