I have two skeletal meshes associated with the same skeleton.
When i create an animation BP and change the mesh (in the picture, going from the zombie mesh to the SuzanneOReilly mesh), everything seems right and works well (the new mesh is correctly displayed and animated).
But i can’t save the change: if i close the animation BP and reopen it, the original (zombie) mesh comes back.
I tried to compile, save, even reimport the new mesh, couldn’t save that change.
I was able reproduce your issue by duplicating the SK_Mannequin Skeletal Mesh and creating the “SK-Test,” both sharing the UE4_Mannequin_Skeleton as shown:
Then I duplicated the ThirdPersonAnimBlueprint, calling it “BodySwitchTest.” In that Blueprint I switched the Skeletal Mesh to the “SK-Test.” Saved and found it reset to the original mesh. This is because you need to set the preview by selecting the “Set Preview” button as shown:
Now both AnimBlueprints and animations associated with that skeletal mesh will change to the newly selected preview mesh. However, while the two AnimBlueprints have the same preview, you can still use both instances in your game as shown here:
In order to make this workflow less confusing, I am entering a Feature Request so that, if possible, different AnimBlueprints can assign different Preview Meshes to the same Skeletal Mesh.
I had noticed that the set preview was saving the mesh but then ran into this “all or nothing” issue, but i didn’t push the test as far as you did and didn’t noticed that things were ok beyond the preview.
As you noticed, it would be nice to display the real thing in the BP, so thanks for having pushed this to the dev team.