Ran into a puzzling issue: I have one specific texture which generates the following error :

I'm using four 256px pngs as input and afaik they have no discernible difference from the other ~30 textures I did so far, nor am I doing anything different.
Also note I'm using version 1.3.0.0. I tried using version 1.3.1.3 this morning but no matter what I try it says 'an invalid header was read' right after selecting the pngs for a new fsh.
