I have no idea why this happens but it works like this:

I copy a graphic or text from outside PowerPoint and when I try to paste it into PowerPoint it will not work. PP acts as if there is nothing on the clipboard.


The solution that works for me is to delete something from the PowerPoint slide.

Yes, it is that simple.

Example:

1. I have copied a graphic from a screen capture.

2. I switch to PP and "paste" is not available.

3. I delete something --- anything --- from the PP slide.

4. Now the "paste" function works; both ctrl-v and from the menu.