When I try to add image into new newsletter content I end up with empty image.
My WordPress version: 4.6.1 (pl)
Steps to reproduce:
1) Create new newsletter from template (default).
2) Put some posts in it and proceed to edit.
3) Put cursor at the end of email content.
4) Click “Choose or upload an image”.
5) Choose image from Library and click insert.
After 1-2 seconds empty image icon appears in content.
In console img code looks like this: <img src="t" alt="" data-mce-src="http://mywebsite.pl/t">