Hello! I've come to say that I believe that the way hunger works in Maso-Mode causes this. This does not occur in Easy(er) Mode, or Fear and Hunger mode.
To potentially solve this problem, I'd look into what changes the hunger stat up in Maso-Mode. Other than that, I literally have next to no clue for what causes the Hunger stat to drop to 0% upon starting a Maso-Mode run, as Easy(er), and Fear and Hunger mode, do not have this issue.