Plague Bug
I saw this already in the forum but i was from 2-3 years ago and still said pending so I figured I'd mention it again. The Purge both corrupt and vile on plague will hit a survivor and causes them to scream but then not register the damage or the infection depending on the purge. Sometimes it works but the hitbox is horrible and feels like something is off.
Comments
That's latency or hit validation, not a bug.
I actually think it's a bug because I had the same thing happened to me and when I watched the stream of a teammate of the survivor I hit, they also screamed, indicating the vomit registered on their side too.