Recently an AE user (N.P.) did some nice detective work and agreed to share his findings with us.
It turns out that at least some versions (for sure 6.0) of Lightroom on the Mac can't read sidecar files generated with the uppercase XMP file extension when reading from a NAS running NAS4free with AFP file protocol.
This issue warrants closer examination due to its complexity. N.P. initially exported files to his local drive using AE as a test, which functioned correctly. However, when directing AE to export to his NAS and attempting to import results into Lightroom, all metadata in the XMP sidecar files was lost.
By default sidecars generated by either Exporter for Aperture, Aperture or Photos have uppercase XMP extensions. As long as these generated files are on the same hard drives/OS as LR is installed then LR sees the metadata in the LR catalog after adding the images. As soon as I tell AE to choose my NAS as the destination of my exported files then LR is lost and does not read and add the Metadata to its catalog. I can get around this by telling OS X Automator to rename the XMP file extensions to lowercase and then adding them to Lightroom catalog. After that renaming all is fine and metadata show up in LR.
Several unknowns remain:
- Whether other NAS units/distributions are affected
- Whether other Lightroom versions are impacted
- Whether this stems from the OS X AFP protocol stack
- Whether this originates from the NAS4free AFP protocol stack
The developers welcome reports from users experiencing similar NAS and Lightroom import challenges.