The blending behaviour of a state with None on the Base Layer is different from a state with None on a Layer. This is caused by a performance optimization for state machines using a single layer. We cannot change this without having a significant negative impact on performance and our user’s existing projects. Since the main use cases for using None in a state is in the context of an additional Layer, using None on the base layer is considered an edge case and has acceptable workarounds.
Workarounds: Use an empty clip on the Base Layer None states. Or, reproduce the same setup an a Layer that is not the Base Layer.
For the above reasons and associated risk, we will not fix this inconsistency in behaviour.