I have the same "feature" with my Soundcard as well , it works fine with Config Audio, in the Windows Speakers Properties screen I also have a Mic Level window and when I use Configure Audio it shows the Mic as muted during playback with N1MM Logger+.
But when Logger+ Audio is used , it shows on the Speaker Properties Mic at normal level and on the Record Properties the level rolls back to -186dB. so the through path is still live.
However if I use the on board Realtek AC883 HDAUDIO that works the other way??? That is
with Logger+ Audio the onboard HDAUDIO work fine and mutes, Providing I set "listen to this device" to ON.
If I use Configure Audio I can't select the MIC to mute on the HDAUDIO chip!!
I have detailed screen snips etc if anyone needs them
Soundcard is Creative Audigy RX 7.1.