I was editing photos in Lightroom Classic 11.0. The image files were not in my catalog--when I imported the images into my catalog I did not move the files. I selected 8 images (.NEF) and then right-clicked Edit > Edit in Adobe Photoshop 2022. Lightroom hung at that point. I retried that two more times. I closed and re-opened Photoshop and tried once more to edit the images, but again Photoshop did not open. I rebooted my computer. Then, when I tried to edit one image, Lightroom said the image was missing. I checked the contents of the folder that contained the images and indeed that file was missing along with four or five other files, some of which I had never attempted to edit in Photoshop. The .xmp files remained on the hard drive. The .NEF files are not in my recycle bin. I tried searching my hard drive but the missing files are not there. I tried using EaseUS Data Recovery Wizard to find them on my hard drive but sadly those irreplacable images no longer exist.
Lightroom Classic does not move or delete your photo files on its own. Even given the hanging issues mentioned, there simply is no feature programmed into LrC to move or delete photos on its own.
When you said you tried searching for the missing photos, do you mean you used your operating system's search feature to do the search? Or do you mean you yourself looked in a lot of folders and couldn't find them?
I don't know what happened to your photos. I am 100% sure Lightroom Classic did not do this. The best suggestion I can give you is to have backups of all of your photos before you work on them.
This is totally unusal. I have never seen Lightroom delete the files. My solution to this issue is that my catalog harddrive is actaully my dropbox folder too. So everytime i copy or move images to my catalog harddrive they also copy to dropbox in the cloud. So all my images are on my local harddrive but also are always backing up to dropbox. I never even have to think about backing up it is automatic. Drop Box can actually retrieve any deleted file from as old as 30 days. So maybe try to include a back up solution in your work flow.
Sorry to hear about your challenge. As others have said, unless you initiated a REMOVE PHOTO with DELETE FROM DISK, LrC should not lose pictures.
You said "The .xmp files remained on the hard drive." but yet the NEF files are gone. Could I suggest you look at the XMP files and see what the name of the files are they are associated with? Here's an example. I'm hoping somehow the files have just been renamed.