To display copy and pasted text and images in OneNote for Mac, try the following steps:

1. Check the format of your copied text or image. Ensure that the item has been copied in its original format and is not in any other application or format.
2. Check the version of your Mac OSX. Older versions may not be able to display certain types of copied content. Make sure your Mac OSX is up to date.
3. Update the version of OneNote for your Mac OSX, if available. If the version of OneNote you are using is not supported by your OSX version, it may not display copied content correctly.
4. Try restarting your Mac, and then try again to display the copied content in OneNote.
5. If the content still does not display, try copying the item to another application, such as Word, and then copy it again into OneNote for Mac.