No Preview on Import!?

[Slobodan Blagojevic]

What causes that some images show up and others do not? Slow transfer rate?

EDIT: I am on LR4.4

[Hans Kruse]

Good question... I have had this happen a number of times within the last 3-4 months on LR4 and also on LR5. If I cancel the import and click import again it is usually resolved. But is seems like a timing problem which is strange and in my book should not happen.

[digitaldog]

The times I've seen this are with PSD's that I assume don't have Image Previews saved in them.

[digitaldog]

Correction, I see this on PSD's when Maximize PSD Compatibility is OFF. I opened one such doc, saved it with my defaults (Compatibly ON) and LR saw the preview. And the resulting document was much larger in size. I see your documents are CR2s which I can't explain. Seems like the embedded preview is missing.

[Eric Myrvaagnes]

What causes that some images show up and others do not? Slow transfer rate?

EDIT: I am on LR4.4

Hey, Slobodan. Maybe it's LR's way of saying "NSFW." What kind of seamy stuff have you been photographing?      

[Slobodan Blagojevic]

I wish

[eliedinur]

Have you tried changing the card reader/usb cable? Do other applications, like Explorer/Finder show the thumbnails?

[Slobodan Blagojevic]

On second attempt, everything was fine. However, I wonder if that is because I already had them imported before, though I deleted the files from the computer afterwards and purged the cache.

I just remember seeing this on occasion before, i.e., that some files show (as is the case in the OP example) and some do not. There was no other difference between files, they are all RAW and shot on the same day, with the same lens, etc.

[thierrylegros396]

Have sometimes experienced same problem with LR4.4 and LR5

[PhotoEcosse]

Occasionally I have noticed this - in both LR4 and LR5.

It's not a problem (for me). As soon as I "mouse-over" the blank image, the preview appears.

[NikoJorj]

It's not a problem (for me). As soon as I "mouse-over" the blank image, the preview appears.

Same for me, I only (but often) see that during an import, when LR has done the file copy and sql referencing but not yet any preview rendering. Solved by waiting a few seconds.
It might well be that somethings hungs your machine in a frozen space-time vortex, or some similar oddity.