Enhance Speech takes audio from both channels when using Fill Left with Right (or vice versa)

Issue as in title - if applying enhance speech to a clip that has fill left with right, or fill right with left applied, you will hear artifacts introduced by the unwanted channel. You can't seem to drag the enhance speech effect lower down in the audio effect heirarchy either, it is locked to the top.

MacOS 14.1.1, Premiere Pro 25.0