I apologize it was my fault all along. I had downloaded your "example" pack, and had extracted it in the same folder as BlastFX_demo.exe. And I was putting my flipbooks in blastfx-windows-demo\examples\textures instead of blastfx-windows-demo\textures
TLDR: It works, I just had 2 indentical folders and was putting my file in the wrong folder.
This tool looks promising! Gonna poke around some more!