Thanks for your reply, but I think I do understand Libraries as far as you're describing - in particular that Libraries are just a "view" across one or many physical locations.
This shows the sort of thing I was doing. I'm accessing files via the Library and moving from one folder (in this case "Abel Tasman - Test" into a subfolder "Day One").
After doing this I'd expect the following:
- HDD via "D:\Shared\...\Abel Tasman - Test\Day One" now contains the files I moved
- HDD via "D:\Shared\...\Abel Tasman - Test" no longer contains the files I moved
- "Library\..\Abel Tasman - Test\Day One" view of HDD shows the moved files
- "Library\..\Abel Tasman - Test" view of HDD does not show the moved files
Instead I got the following:
- On HDD, viewed via "D:\..." directly, the files were correctly moved (no longer in "Abel Tasman - Test", now in "Day One")
- Viewed via "Library\...", the files were present in both "Abel Tasman - Test" and "Day One". Clicking "Open file location" sent me to "D:\Shared\...\Abel Tasman - Tes\Day One" in all cases. In other words, the Library view was showing a duplicate view of the files as if they were in both folders on the HDD, but both were pointing to the one physical location ("Day One").
I had one even weirder example too. I had copied files into a folder on the desktop first. Then I copied that folder (drag'n'drop style) into one of my photos folders via the Library again, very similar to what I'm describing above with the Abel Tasman photos. Then I deleted the folder from the desktop. Now, you'd expect by this time that the photos on the HDD in the "D:\Shared\..." would be completely independent. But after I deleted the folder from the desktop, I discovered that the files had been deleted from "D:\Shared\..." as well.
One theory: windows Library isn't actually copying/moving files onto the HDD when I do this drag'n'drop, but is instead adding the source folder as a "library location". This is what clicking into Properties looked like when I encountered this problem when right-clicking the "Pictures" library:
There's no mention of any of the sub-folders, let alone individual files, just the two root folders I'd added a while back.
Second, when accessing the D drive directly, the files had always been moved/copied correctly, and in the case of moving no longer remained in the original location.
I'm now unable to replicate the problem further - I just created images above to show what I'd done a couple of days ago. But I still hope I can find some explanation to this so I can avoid data loss later. Until then, I'm very afraid to access my photos via the Library interface - which is a shame because I happen to like the idea.