Originally Posted by
Clactonian
Russ, you do not describe your actual workflow, but assuming that you start by exporting an image from LR to an external editing program such as PS, if you simply 'save' the image in PS6 it should reappear in your LR catalogue alongside the original. I always check the 'export a copy with LR adjustments' in the export dialogue box when sending off an image for editing in PS.
Also check by right clicking on the stack images the stacking status. You can of course change the settings to unstack all images, which may well answer your problem.