ML Deformer affecting components other than trained geo

I’m trying to use the ML Deformer applied to metahuman head geometry, but it’s affecting all the components of the face - teeth, eyes, lashes etc. Even when the geocache only contains the head geometry, after training it still is altering the other parts of the face. I’m using the Vertex Delta Model with 5.4, which despite not being recommended is the only model I can actually get to work. I tried isolating the bones to exclude the eyes etc, it has no impact.

In 5.2 I tested with essentially the same configuration without any issues, I never saw it affect the other geometries beside the head.

The head itself is deforming correctly and it looks great. Anyone have a clue how to solve this?