Steps to reproduce:

First way:
1. Open attached project
2. Open "offline_scene" and run it
3. Start and stop server - notice that editor doesn't hang
4. Start and stop server again - this time editor hangs once "Stop" button is pressed

Second way:
1. Open attached project
2. Build and run project
3. Start executable as server
4. Get back to editor and run "offline_scene"
5. Start as client
6. In editor, disconnect from server - Editor freezes

Removing Animator component from the AnimatedControlledNetworkObject prefab makes this bug no longer reproducible

Reproduced with: 5.6.0b1, 5.6.056
Not reproducible: 5.5.1p1