My NextGen gallery kept vanishing on my WordPress frontpage. It did not show as long as the page was set to front page, as soon as I picked a different front page, the images reappeared. Even when I changed the theme, the gallery disappeared.
I checked and rechecked the source code, but what I apparently missed was the gallery being wrapped in auto excerpt tags:
&lt;!-- Begin :: Generated by Easy Custom Auto Excerpt --&gt; &lt;div class="ecae"