Hi @Aitchess, yes, I reckon I can help with this.
Can you go ahead and do your raw processing on the photo in the usual way, then post it again for me?
Hi @Sancurtis, this happens to everyone from time to time, don't worry.
It simply means your layer thumbnails have been turned off.
Click here:
And choose "Panel Options".
When that window opens, you'll find that your Thumbnail Size has been set to "None". Change it to a larger size.
I suppose it must have, yes.
As long as you've checked that you've got the real files, and you can open them, then I see no reason not to delete these weird "dot" files.
That's such a good question!
It doesn't matter when you do it. Early or late in the workflow, no big deal.
If you only remember it at the end of the edit, that's okay. Just return to the Background layer, duplicate it, and blur.