I picked up Skinn Pro for a fairly specific reason: I wanted to rename some blend shapes in some characters I had, so they'd be consistent with my older characters (and their associated facial animation files).
Everything appears to work when I click the context menu for the Skinned Mesh Renderer on the prefab, then go Skinn: Edit -> Shapes -> Edit Names. After I manually rename a shape however, or import a textasset filter to do similarly, everything appears fine at first, but once I save the prefab and return to it, the mesh reference is missing and the character is consequently invisible. Reassigning the correct original Mesh doesn't resolve the issue. I also tried doing a mesh combine, then making the blend shape name changes to the combined mesh. Same issue.
No errors or warnings appear on the console.
I did see your post re: mesh compression=off and read/write=true, as well as keep quads=false in the model import settings. These settings are set accordingly.
This is in Unity 2019.4.14 using 0.71 of Skinn pro.
Any advice or thoughts?