P: On exit, LR doesn't save the metadata of the current photo

I reported a similar error. LR11 does not save to xmp's at all. Pause option in saving xmp is off. Only by selecting all images and choosing the option "save metadata" shows the xmp's are created.

Just a thought, a ‘Saving XMP’ pause button was added in activity centre to pause and resume the Auto Save into XMP (see below screesnhot). This  button is only displayed when ‘Automatically write changes into XMP’ option is enabled in Catalog Settings, but I see no mention of checking status of same in your post or similar posts by others. Can you check status of button.

Another demonstration of this bug: If you try to exit LR while the current photo and other photos have unsaved changes, LR will tell you that it isn't finished writing to XMP and ask if you really want to quit. If you cancel the dialog, wait until LR finishes writing XMP, and then exit, LR still hasn't written the metadata for the current photo, even though it has for all the other photos.

To reproduce:

1. Select over 600 photos, with a raw most selected.

2. Go to Develop.

3. Turn on Auto Sync.

4. Set Exposure to -5.

5. Immediately after the Synchronize Settings progress bar completes, try to exit LR.

6. When the dialog asks, "Adobe Lightroom is not finished writing metadata changes into XMP, do you still want to quit?", click Cancel.

7. Repeat steps 5-6 until the dialog doesn't pop up -- that is, until LR thinks all the metadata changes have been written.

8. Edit in a text editor the .xmp sidecar for the file edited in Develop in step 4.

9. Observe that Exposure2012 is not -5, indicating that its metadata didn't get saved, even though all the other files had their metadata saved.  Bug.