Can't find denoised DNG file in Library module in Windows

As suggested above by @Rikk Flohr: Photography , please try deleting your preference file.

https://www.lightroomqueen.com/how-do-i-reset-lightrooms-preferences/

So, after LrC accomplishes the AI Denoise, you should have a new file, a new photo with a file name with syntax 

????-Enhanced-NR.dng

(where ???? is the old file name such as _DSF0247)

You can search on that, either in LrC or in your OS File Manager, to see where the heck it went. Do that before restarting LrC as to see if it is just hard to see.

Hello,

I had this very problem you are describing! I could not resolve this issue. My only solution was to create a new catalogue.

In order to keep all the settings from the old catalogue, I had to Export as Catalogue and Import it into the new catalogue I created.

It took a while and jumping through a few hoops, but worked out in the end.

You won't find any solution here as I looked. I don't think this is a common problem. I think your only solution is to create a new catalogue.

My issue wasn't related to Denoise, but merging HDR or Panorama, but the mechanics are the same. It's merging or creating a new DNG file that seems to be the problem. Only when Lightroom was restarted, did the 'missing' file reappear.

There have been occasional reports here in this forum of photos that can't be found until Lightroom Classic is re-started. I don't remember if any of them are related to DeNoise. I thought this issue was solved at some earlier version of Lightroom Classic, but apparently not. Unfortunately, as this bug does not affect most people, it is probably difficult for Adobe to reproduce and then solve.

Expand all stacks (Photo->Stacking->Expand All Stacks)

If that doesn't work

Sort by file name (View->Sort->File Name)

Check if the denoised DNG file has been stacked with the original.