Which operating system are you using?
Did you checked the External editor setup in Lightroom preferences and ensured that it is set to open Photoshop elements?
From the Lightroom Library go to:
Edit >> Preferences >> External Editing (tab) Windows
Lightroom >> Preferences >> External Editing (tab) Mac OSX
Yes, I check that and also added another instance of it. It seems that LP is not passing off the file correctly because PSE opens but does not open the file.
Everything was working properly prior to updating to LR 6.9
I do not have Elements but have read about similar problems to yours. I would check the External editing preset again and confirm that Lr is pointing to the Elements Editor (and not the Photoshop Elements.exe 'preloader')
Have a read of this link-
Yes I've checked, changed, tested, that route. Several times. Still no luck. I am almost to the point of removing elements from my computer and reinstalling it.
After I hit OK, The file appears in PSE, ready for editing.I can edit, save and exit and the new file is in LR with the edits. If I exit PSE, the same thing happens next time. If I leave PSE open, the same thing happens.