Reasons copy/paste not functional within same tab

I'm unable to copy/paste rows from one sheet to another. I want to paste special, so using right-click 'copy to another sheet' doesn't work as I don't believe it offers that option. I've stayed within the same tab to open the target sheet. I've also tried using keyboard and mouse commands. With the former, it just does not paste and with the latter, paste is greyed out. Any advice appreciated.