Ethan,
Catalog to Sync skips over existing files, but Scan to Catalog seems to always trigger metadata gathering and preview generation. I haven't seen it not do so in all these tests.
OK, I'll test that locally.
For whatever reason, after moving most content of /scans to /scans/hidden, testing on a test catalog, and moving everything back, I can no longer replicate the duplication issue. Images are back in their original position under /scans. After one more time removing cat_state.sq3 and reintegrating, the main catalog seems to be working as expected with the /scans images: no duplicate images if I Scan to Catalog a second time, and I can add and remove images as expected. Unless the issue reappears, I won't be able to get you a new log.
So very strange.
A maybe (not) related issue regarding the files in /scans: Many are large (~200MB+ 48-bit RGB TIFFs), and despite them being in a catalog with presumably complete 1600 px preview proxies, their thumbnails/previews sometimes load very slowly (and closing the contact sheet prematurely results in a spinning wheel for several seconds). Does this sound like an issue with my catalog? Or are proxies only used when the source images are not connected?
Not an issue with your catalog. If the images exist locally, they're loaded directly. If they're offline then the proxies are used.
Is there a way of checking that the proxy for an image exists and is being used?
No. It's a feature I'd like to add. It would make working with NASes much better.
p.s. I noticed that proxies of small images are larger than the images themselves. It seems a proxy should be no larger than the source image?
Ideally, yes. We consider it a bug. Unfortunately due to the architecture of the system it isn't trivial to fix.
-Kirk
