I export image from LR to edit in PS. When I want to "Save", which is set up to Save as an edited duplicate file on LR, the progress bar show 10% immediately, but remains stuck there endlessly. I have to Force Quit PS to get anywhere in PS. LR is fine, I think. Its the saving back. What is going on?
Concentrate on why Photoshop can't save. Lightroom has nothing to do with this - it's just a background script that keeps track of the file and adds the location to the Lr catalog.
You never save "to" Lightroom. Photoshop just saves to a location on disk just like it always does, with or without Lightroom running.
If the Photoshop save never completes, maybe it's a permissions problem on that folder.