I choose five photos, click on Share and then Email. I usually choose the Medium format.
A download progress bar appears showing that the photos are being downloaded and then the email form opens. The Subject line says "Five great photos" but only two appear. I have no idea what happened to the other three.
I have re-tried this over and over, and re-booted. Sometimes none of the selected photos download to email. I get Subject: "Five great photos" and a blank field.
This morning I was able to email 10-12 photos at a time without a problem.
I have no idea what may have changed since then to cause this problem.