Maintain Copy / Paste
For some reason if you copy a cell (ctrl+c) and then do something else in the workbook (for example enter text in another cell), Excel clears the pasteboard and you can't paste (ctrl+v) the text any longer. Excel needs to be able to maintain the pasteboard so that copy / paste can function normally.
YES! This is most annoying/aggravating. WHY did you have to change the way that this has worked for decades????? Please find the blithering idiot who changed this and take away their tinker toys.