If you go to the Catalog tab and choose "All Photographs" can you see if the photos are already in the catalog?
Do not assume Lightroom is a file browser. It is not a file browser. It doesn't "see" photos in your folders.
If your 754 photos cannot imported via synchronize, it is because they have previously been imported, and are not going to be imported via synchronize (or any other way) again. Furthermore, Lightroom thinks these 754 photos are in a different folder ... why? ... because when you imported them previously, you (perhaps accidentally) asked Lightroom to copy them to another folder.
So, you need to go into the Library Module, and then follow all four of these steps in sequence
- In the Catalog section on the right, click on "All Photographs"
- Turn off all filters, Ctrl-L once or twice
- Expand all stacks ... use Photo->Stacking->Expand All Stacks
- Search for one of these 754 photos using the file name
This will find that one photo (and presumably the other 753) and you can them make use of them as needed in Lightroom. If necessary you could also instruct Lightroom to make use of the copy in the desired folder.
Thanks for the quick response, 99jon and dj_paige. I'll be back to it shortly and try as you suggest. "not a file browser" seems to be a key phrase for me to consider. I'll let you know how it goes.
It still took me a bit to figure it out but I'm pretty sure what happened is that the files I couldn't see were named the same (and were the same) as ones that were already synced on Lightroom. I just had to give Lightroom permission to sync images that were duplicates.
Thanks for your help. I'm getting closer to a full understanding of Lightroom.
The general idea of allowing duplicates solves some problems, but causes other problems. In particular, edits and metadata you apply to one of the duplicates will not appear on the other one of the duplicates, unless you take some manual action.
In the long run, you'd be better off not allowing duplicates.
I am having a similar problem. When I sync files, LR will no longer import photos in subfolders. It mentions them (e.g. Import new photos (1)) but it won't actually import unless I sync the subfolder.
This has been explained earlier in this thread. Please try the solution suggested there.