Please check and make sure that the image you trying to edit that should be available not missing from Lightroom.
Let us know if that helps.
At first that was a problem and I connected the file. Still did not work. Rebooted the system. Tried again, no luck.
Sent from my iPhone
Please uninstall all versions of Photoshop from your machine, restart and reinstall it from the Creative Cloud.
Let us know the outcome.
Deleted Adobe Photoshop and cleaned all cashe, files, preferences.
Turned off computer, turned on computer and ran CleanMyMac3. Rebooted the computer and then re-installed Photoshop.
Rebooted the computer, opened Lightroom and it showed Photoshop and when I clicked it to edit-in Photoshop, it never started Photoshop. I opened Photoshop and then tried Edit-in Photoshop from Lightroom and it still did not work.