Denoise not working

Hello, I’m trying to use the denoise feature to obviously reduce noise but its not working at all. There is no error message but it'll allow me to preview the image and apply the denoise and I’ll wait the 15 minutes or so for it to finish but once it’s done, it literally hasn’t done anything. The preview shows the image in perfect quality of what it’ll look like when it’s done processing but once it’s done, nothing has changed. It used to work perfect when I first started using it but now it’s not working with any of my photos