I noticed that when pasting into a richtext form section in a /application/<aId>/form/question/<qId> URL that sometimes the text appears without paragraph spacing, and that this is impossible to adjust subsequently. However, after submission, a reloading the page, the server has fixed this up.
I can't reproduce this immediately, but the similar scenario of unstyled paste is 100% reproducible (using Mac/Chrome71) by pasting in multi-line text using Shift-Modifier-V, i.e. paste with shift to use the unstyled clipboard entry.

Pressing return to add a new line in the normal way then continues to use div tags rather than paragraphs:
