Add photos to one collection, removes from another temporarily

[sbsmithjax]

Greetings,
I have LR 1.4.1 on a Vista machine. I love LR, but am having an issue that is now coming up. I have approx. 36K photos in my catalog, it is backed regularly, and optimized. Here is the problem:

I have a set of photos, let's say 2' photos in a collection called "Ashley".

If I highlight 1' of those photos and drag them into a colllection called "Dad", then LR *appears* to remove them from the Ashley collection.

There is nothing I can do to see them again in that collection, except restart LR, and then they are right back in that collection.

Any ideas what causes this/how to fix?

many thanks,
stephen

 

[RikkFlohr]

When you grab the 1' shots of Dad and drag them into the new collection, are you dragging them from the Ashley Collection, the Folder, or from all Files?

When you look at your left pane in your Library, what is highlighted when this happens?