This concerns the table view of Base: Starting a few updates ago, you cannot use "strg c" and "strg v" anymore to copy the contents from, for example, the line above into the new data line, the term you want to copy appears for a fracture of a second in the new data line then disappears and the data field is empty (i.e. no contents, not just invisible). The context menu ("right click") works as intended but not the shortcuts. So you have to switch from the keyboard to the mouse to copy and paste something.
Seems to be a duplicate of Bug 140992. I will mark this one as duplicate. Feel free to reopen if you think it's another bug. *** This bug has been marked as a duplicate of bug 140992 ***