Noise reduction not working

So my speaker made a buzzing sound while recording and I didn’t realize and normally noise reduction works fine for that but for some reason it isn’t working, it works on the preview fine and it works if I do it 3 seconds at a time but its a 12-minute audio clip and I don’t have time for that so does anyone know a fix? I restarted my PC and audacity, I tried running audacity as administrator but that didn’t work either.

If the buzz changes pitch or timbre during those 12 minutes then the initial noise-profile will no longer match the unwanted sound.

If the buzz is mains-hum there a plugins specifically for that which are worth a try.