I can confirm that this still happens as of 41.71 and I can add a bit more insight.
I'm the developer of the Night sprinters[41.60+] mod on the workshop and my mod suffered the same bug for the longest time. Through my testing I think I have an explanation as to why this is happening. I believe, on a server, there are 3 kinds of zombies: 1. zombies loaded onto the client and server(green) 2. zombies that are not loaded by either(red) 3. zombies that are loaded onto the server but not the client(orange). I might be wrong, so I included a picture of what I'm talking about on the zombie population map from the debugger.
The problem is that the 3rd zombie type is not changing correctly. For whatever reason, these zombies keep their active/inactive status from when they are loaded by the server when they are then loaded in by the client. So if they are active when they are loaded by the server and change from the 2nd type to the 3rd type they will keep their active status when they are then loaded in by the client and change from type 3 to type 1.