When I double-click on a file that should open in Photoshop, it goes through the motions, but doesn't actually open the file. I have to do File...Open.
Please note the file association is not broken. It still says "Open with... Photoshop" as the default. And I reset that association just to be sure. I've also restarted.
See the video attached. You can see when I double-click the file on the desk top, it "expands" like it's opening... but no file actually opens. There's nothing in the Layers palette, and there is nothing to Close. But when I do a File...Open for the same file, it opens fine. This has never been an issue until a few days ago it seems.
I am running High Sierra 10.13.6 on a mid-2017 MB Pro. My Creative Cloud is up-to-date, and it looks like I am running PS 20.0.6.