A few older files seem to have lost their edits

[Printdevil]

Looking at my older photo shoots I can see that a few of them have lost all their edits. I still have low resolution JPG exports as a reference but all the RAW files are back as they were straight out of my Nikon camera. I can see all the XMP files are still there alongside the NEF files but when I open them in a text editor I can clearly they have all been reset.

I should point out that these files have been transferred to an archive drive, but this is something I do on a regular basis but the edited XMP files always transfer to the new drive along with the RAW files. I can see the majority of all my other shoots have retained all their edits.

Unfortunately I don't have any Lightroom catalog backups going back to 2014 so I am assuming these will need to be re-edited if I want to restore the work I have lost. I don't mind doing it for a small shoot but I would be distressed to see this happen on a big shoot so I really want to prevent this from happening again.

What could cause just the odd shoot to lose data from the XMP file?

David

[DdeGannes]

@Printdevil , you stated "  but all the RAW files are back as they were straight out of my Nikon camera. I can see all the XMP files are still there alongside the NEF files but when I open them in a text editor I can clearly they have all been reset." 

The edits you did to your NEF files are in the XMP file only applications that can read those edits are LrC  and Adobe Camera Raw.. What text editor are you referring to.?

[Printdevil]

I can see all the XMP data in Apple TextEdit.

If I compare the data in this file where the data has been lost to the XMP file that has been edited I can see loads of differences in the text.

[DdeGannes]

Apple TextEdit would read what "Metadata" it can from the XMP file but it's not able to read the "Edits" to did in LrC Develop Module. 

[richardplondon]

an XMP file viewed in a text editor will report a list of Develop adjustment parameters and what each one was set to when this XMP was last updated. LrC may not have been set to write out its latest edits to XMP at the time those were carried out. In that case the Catalog concerned would hold newer editing info internally, than was visible in XMP externally. There may even have been no writing-out of edits by LrC in which case no XMPs might be present.

One way that XMPs may be now seen which contain no editing, could be if these photos had been meanwhile imported to some different Catalog, arriving as 'unedited' due to lack of accompanying XMP, from which an 'unedited' image state could then get newly written out as an XMP file alongside the Raw.

As a costs-nothing check, you might see whether the images concerned show any Snapshots containing possibly useful editing - these would be visible once a Raw's brought inside a Catalog or else inside ACR, having been read in automatically from the XMP sidecar. Just in case the images had been Reset at some point and then the external XMP overwritten with that, only Snapshots could still retain prior image states. Other than, a Catalog's history panel earlier than this Reset, or an earlier Catalog backup without this, or a prior disk backup showing XMPs that still reflect the prior edits.

Some clues about what's happened may be gleaned by looking at the file modification date of these XMP files, reporting when their contents were last updated. This would normally mean either a LrC Catalog wrote out its metadata on demand / automatically as you edited; or else ACR wrote out its metadata assuming you had separately opened these Raws into that - and then either proceeded into PS, or else clicked Done when exiting the ACR window. 

The basic answer to prevent all this happening again is IMO to ensure you retain a copy of the relevant Catalog showing those edits in place. XMP sidecar files are only ever able to convey partial information regarding the work done in LrC - and convey nothing at all, for virtual copies say. A Catalog embodies not only edits, but a history of edits, and its own organisational context too.

[Printdevil]

Some great advice there Richard, I shall do some investigating into the backups I have of old Lightroom catalogs. Just to add another layer of mystery to this story I have found a wedding shoot that I did in 2010 which has lost all the RAW edits EXCEPT for the cropping! So all the images are as I cropped them but all the sliders have been reset. How could that happen?

[dj_paige]

Transferring to another drive and relying on XMP isn't the recommended procedure, the procedure is to move the photos (using your operating system) and then reconnect in LrC so that the edits which are in the LrC catalog are still available to the program and applied to the proper photo.

Something has interfered with your process, the XMP files have become empty, and I don't know what could have caused this. However, if you have no catalog backups, and the XMP files are empty, then your edits are gone.

[Printdevil]

Yes I think your assumption is correct but I can assure you that when I transferred my images from one drive to another within Lightroom the edits definitely went with it.

Something has happened in the interim to cause the edits to be lost. I have helped enough novice Mac users in my life to know that things don't "just happen" and it is often user error so I am sure something has triggered this to happen to just a few shoots. It's bizarre that I have older shoots where the XMP data has been retained. I now feel duty bound to go through all my photo shoots to see if they have retained their edits.

The problem is that my backed up RAWs and XMPs are all exact copies of what I have on my current archive drive therefore the backup drive also contains XMP files where the data has been lost.