Lightroom: Smart previews disappear for modified pictures

This issue should be fixed in Lightroom 2015.6/6.6 or later.

Do I have your steps correct?

1. With Hard Drive attached. Create Smart Previews
2. Develop some images
3. Detach hard drive so originals are offline
4. Images developed in step 2 do not have Smart Previews - all other images do.

Sorry for the time it took me to answer, but I wanted to make sure I can reproduce the problem. I can say now it is actually related to virtual copy. Here are the exact steps I just applied which cause the problem:
- Import the pictures from SD card to hard disk with "create smart previews option"
- Hard disk attached, create a virtual copy of a picture
- Remove the disk
- Delete the virtual copy => the smart preview of the original copy disappear
- Attach the disk again : the original copy shows only "original image". All other pictures have "original image + smart preview".

Has the bug been corrected in LR 6.5 ?

This reply was created from a merged topic originally titled LIGHTROOM - Deleting a virtual copy deletes the smart preview for both master and....

Reproduction steps:
1. Create a Smart Preview for a photo (Libraries module, Library=>Previews=>Build Smart Previews)
2. Hide the original file from Lightroom (e.g., rename the original file, disconnect the drive it's on, etc) so you're working with the Smart Preview when doing your editing.
3. Make a virtual copy of the photo (Photo=>Create Virtual Copy)
4. Delete the virtual copy
5. The MASTER photo which was not deleted no longer has a smart preview.

Smart previews should only be removed when all copies of a photo that could potentially use that smart preview are removed. This bug has persisted across several version upgrades.

I keep my primary files on a big slow RAID and edit smart previews on my laptop a lot, and often use virtual copies to have one color and one black and white version of an image. Sometimes I decide I don't want the B&W, or just decide I want to go back and create the B&W after making a few more edits to the original, so I run up against this bug a lot in my workflow.

Any news about this bug reported 3 months ago ? Smart Previews are almost unusable in my case, very annoying.

We are fixing the issue: that's while deleting a virtual copy, smart preview of the original disappears.

Thanks,
Sunil