Survivors infected by Plague emit no infected sounds
Survivors affected by the Plagues vile purge do not emit the infected sounds. There is no coughing at all, when broken the puking sound is faintly audible, but still neither coughing nor injured sounds. That heavily impacts playing the game as Plague, since surv can stealth away even if infected, which effectively takes away the only remaining effect working in favor for the plague if survivor refuse to cleanse (finding new victims fast).
How often: Two games played, both had the issue, with every survivor affected by Vile Purge.
How to reproduce: Just start a game with Plague and infect someone, I guess?