Lightroom Classic not importing all files

[ndcahill]

I noticed that my Lightroom catalog was missing photos that were in the folders I had imported. For instance, I have a folder with 73 files - 71 .dng files, one .mp4 movie, and one jpg, but only the one jpg file was imported; or another folder with 36 jpg files, but only one was imported. If I try to synchronize the folder with missing images, LR asks if I want to import the other 72  or 35 or 392 files, and then I get "Importing files..." but then "No photo or videos were found to import." I thought perhaps it was because they had been previously imported, so made a brand new Lightroom catalog, but the same thing happens. Copied the images to a new external disk in case something on that disk was flaky; exact same problem. Some folders are fine; others refuse to import no matter what I do. 

I'm trying to catalog one enclosing folder with 71 subfolders, about 12,000 files (336 GB) mostly .dng and .mp4 files from a DJI drone.

Using MacOS Big Sur 11.6.2, Lightroom Classic 11.1 Build 202112022200-7fd1f998. The files are on external Western Digital 10-14 TB drives.

Thanks for your help!

[ndcahill]

Further: tried to import one of the faulty folders on its own by dragging just that folder into the Import window. I get the full set of images but grayed out, and LR says "this appears to be a duplicate of another photo already in the catalog." But that is not true. I have imported these photos into other catalogs which I'm not using any more, but can't you have the same photo in more than one catalog? 

[dj_paige · Accepted solution]

When Lightroom Classic refuses to import photos, it is almost always because the photos have already been imported into this catalog. So you need to do a thorough search in your Lightroom Classic catalog by following all four of these steps, in order:

1. In the Lightroom Classic Library Module, on the left, under Catalog, click on All Photographs
2. Turn off all filters (Ctrl-L once or twice)
3. Turn off all stacking (Photo->Stacking->Expand All Stacks)
4. Search for at least one of these photos by file name using the Lightroom Classic Filter Bar

[ndcahill]

Thank you! That was the problem: there was a folder of duplicates which prevented the import of the main folder. Removed that and reimported, and it seems OK now. Many thanks!