This has been occurring since 2021, and I'm confident that everyone has experienced it at least once if not many times , It mostly happens with the zombie infection: if you hit a human at a certain position, the ZR config won't register the hit and will only show blood because the infection did not occur, After some research I realized that the command zr_infect_max_distance in the ZombieReloaded config is causing this issue. The default value that set to "80.0" intentionally limits the distance between a client and an attacker for a successful infection, To unlock the infection distance and prevent incidents like the one shown in this video, it's best to set the value to "0.0" This will make it even for both humans and zombies especially in knife combat
knife bug.mp4