Ok Bob

If I go back to the track that I inserted a custom style on using Choir ahhs,
And then click on insert custom style again it come up with the last settings in the insert custom style screen, if I change the voice patch say to trumpet, it looks as if it has taken in the mixer but when I play, it reverts back to choir ahhs and so does the mixer display.

However if I just choose a mid voice patch for that track in the normal way it does indeed change, and sticks playing the custom style track with my chosen mid voice.

So I can confirm your findings (I think)
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