Versions: nibble-markdown 4.0.2 and nibble-markdown 4.0.3
When creating / editing posts or pages the Upload Image link doesn't work but Insert code does.
Edit Line 9 in file admin/views/post/includes/nb_media.bit.
Change
<div id="nb_media" class="reveal-modal">
to
<div id="media_modal" class="reveal-modal">
Reference: https://github.com/dignajar/nibbleblog-markdown/issues/2