Updated to 0.41c
I used the mass converter in the night, and it crashed on one field. When I checked it, the alpha layer for one text layer from before I code-combine alpha and diffuse was missing, meaning the final tiff was all diffuse and was missing the alpha channel (my code didn't catch that).
I don't think my missing a channel problem was recent, but in 0.40, it didn't crash or gave any error. Here it just crashed / closed.
I know this is the culprit because I could identify the field it happened with based on the last .tex.tmp generated. Fixing my layer problem, the converter worked as intended.
Updated to 0.41c I used the mass converter in the night, and it crashed on one field. When I checked it, the alpha layer for one text layer from before I code-combine alpha and diffuse was missing, meaning the final tiff was all diffuse and was missing the alpha channel (my code didn't catch that).
I don't think my missing a channel problem was recent, but in 0.40, it didn't crash or gave any error. Here it just crashed / closed.