New folders of files never appeared in catalog (but have been imported - it says)

[stonecherub]

I loaded three days worth of drone images into my (not Lightroom's) catalog of images (managed by IMatch) but only the third day (29 images) shows up in the Lightroom Library navigator. Heretofore, every time I have added new images, they showed up immediately (see below).

I can look at a whole-screen version of my Lightroom catalog and see those missing images, but they are grayed-out. A pop-up says that they have been imported. 

While working with last weekend's stuff, I found a lost chip from an earlier trip, read it into the existing catalog, and those images became immediately available!

[dj_paige]

Files that won't import because Lightroom Classic says they have already been imported, you have accidentally imported them into the "wrong" folder, and can be found by searching the Lightroom Classic catalog as follows

1. In the Lightroom 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 Filter Bar

5. Once you find such a photo, see what folder Lightroom Classic thinks it is in

[stonecherub]

My DJI Mavic drone flies for about 25 minutes on a battery. After a recovery, I change both battery and Micro SD chip. After chip format, images are numbered sequentially starting from 0001. In a file manager, images from each chip are renamed year-mo-da-nr to make a day 'dng' folder with all the day's work in sequence. A lot of image name manipulation Lightroom never sees.

After having removed all the 2021 folders from LR catalog, I re-started LR and found all the 2021 day files in my catalog on the left. When I selected day 30 'dng' folder, my images appeared grayed out and the "import" button on the right is also grayed out. If I hover on a photo, the pop-up says "This image has already been imported."

Yet, when I search for one of the files as you suggested, it's not there!

[stonecherub · Accepted solution]

I hate problems that "solve themselves!" This morning I tried to revert to the back-up copy of my catalog which I have never done before. When LR re-launched into that catalog, my images from this past weekend were in that supposed back-up file dated in December of 2020. 

At this point, I don't have time to research how or why this happened, I have work to do.

Thanks to everybody who tried to help me.