Copy & Paste Not Working (iMac)

When I copy and paste text from the internet to Microsoft Office, it stops working for a while. For example, I'll copy and paste text back and forth for maybe 10 or 15 times, then no matter how much I copy the new text, it still keeps pasting the old text. The copy/paste clipboard just doesn't recognise the new text being copied.

This doesn't happen on the same program. I can copy/paste as much as I want within Microsoft or within Google Chrome, but this problem only occurs between programs.

To reset it, I have to either quit the programs or copy random text on Google Chrome and then paste it into any search bar.

This does not happen on my iPhone or my iPad, just the iMac.