I took a screenshot of a window, then I copied it to the clipboard and finally I tried to paste it into a Google doc by using Ctrl+V and the option "Paste". Nothing happened. I tried Firefox in safe mode and cleared the cache and cookies, but the problem continues. I use Linux, so I thought that maybe in Windows would be different, but the problem occurred again. Finally, I installed another browser (in Linux and Windows) and the copy and paste functions worked. I looked for a solution, but nothing seems to work.