Recently upgraded on my sandbox WP install (not visible main site). Glad I wanted to do some testing and didn't upgrade the main site. Seems that I can write and publish posts & pages fine, same for when I go to edit a page with edits made.
However once an image has been uploaded and dragged into the WYSIWYG edit box and saved, the page will for then on fail to save any changes.
Basically, once an image is added, the page will save with the added image, but no changes at a later date after that edit will be saved.
It is very strange, wondering if anyone else has run into this problem?