I was trying to add an unordered list into a text box (using the Source code edit) like so:
When I click "OK" it appears in the WYSIWYG window, but then hitting "Done" on that causes the entire box and the text within to disappear from existence. This error occurs on both a new text box and an already-existing text box.
I experienced this on Windows 7 64, Chrome version 44.0.2403.130 m. Lay Theme v 1.035 and Wordpress v 4.2.4
Will let you know if I see this in any other browser or on OS X!
Edit: also happens on Windows Firefox v37.0 and Mac OS X 10.10.3 Chrome v44.0.2403.130 (64-bit) --
However this error does not occur on OS X Safari 8.0.5 !