Tag-galleries break when using Chapter slug-name

Using Comic Easel theme by Frumph (Phil Mofer)

I don’t know if this is Easel’s end or Nextgen’s end, but I thought I’d let you know. I was trying to organize my nextgen gallery by tags. I used tags of images relating to chapters. But when I used the same tagname as a chapter slug, it would cause the gallery not to show up. What’s up?
Example: Chapter name: Rose | NextGen Image tag: Rose = tag-based gallery not showing up

http://wordpress.org/extend/plugins/nextgen-gallery/