Attempts to copy or copy-picture from Excel 2008 (Mac) and then paste into Notes e-mail often do not work. An alert is the result: “Unable to get data from clipboard”.
A workaround is to paste first into something else like TextEdit, then copy and paste from that into Notes. This has always worked for me.
Attempting, in Notes, to Paste Special - Picture, produces the alert: “Source Application cannot render clipboard metafile”. Pasting Special as text or rich text does work, but not for plots.
As I was collecting details for this post, everything started working perfectly again. So the problem is intermittent. Very odd.