Steps to reproduce:

• in an XmlText attribute, create 2 paragraphs
• between the 2 paragraphs, add an empty one
• add a quote custom tag in this empty paragraph (or any block custom tag)
• right after adding the custom tag, start typing some text

in Chrome, the second paragraph content is added in the quote tag, in Firefox, the quote seems to disappear.

Expected behaviour: the 2 paragraphs should remain unchanged and the typed text should appear inside the custom tag.