HELP. Updated Photoshop to 21.0.2 — and now all files are appearing as totally black screen

Just updated Photoshop to 21.0.2 because of some serious lag / hangtime -- and now every file I'm attempting to open shows a totally black screen, as if there's no file open at all. There's not even an outline of a file visible -- just pure black. But all layers are visible, images are large so it's not a zoom issue... What broke??

Please help?

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