I select a layer. It is clearly highlighted by the bounding box. I press CTRL+C and then CTRL+V and the previous thing I copied is pasted. I try again, same thing. I stare at the keyboard and press CTRL and C to be sure I'm not making a mistake and it still pastes the previous item that isn't selected and clearly wasn't copied.
I go to the Edit menu and press Copy and then press CTRL+V and it works.
I have done this same process at least five times in this document. Each time I am absolutely 100% certain I pressed CTRL+C and Photoshop randomly decides whether to put the object into the clipboard or not.
Why in god's name is a feature from the '70s tripping up Photoshop? I just want to copy/paste objects. I'm not trying to be cutting edge here!