Animation Retargeting Source and Target Meshes empty

Using 4.20 I’m trying to retarget the animations from one mesh onto another. The two meshes are in the same base pose (A-Pose) and they both have their preview mesh set, but when I try to retarget, neither of the meshes show up in the retargetting window and I can’t re-target the animations.

If I just ignore the fact that neither of the meshes is displaying, I get the error:
“…need to have preview mesh setup to convert animation” but the preview mesh is set and applied. I don’t know what I’m missing.

Okay, so apparently when you choose the preview mesh, hitting the apply button once doesn’t work. You literally have to keep hitting it at random intervals until you see the asterix * appear in the mesh. Then it will actually apply the stupid preview mesh. Why this isn’t automatic is beyond me. Stupid UE4!