I can confirm that i did all of the above.Just confirming that you did all of the following.
1. Stopped the server/exited the game for client host.
2 Manually edited the existing entityclasses.xml or uploaded a new entityclasses.xml with your preferred changes.
As an example, with an entity such as the Scarecrow in the entityclasses.xml:
<entity_class name="zombieScarecrow" extends="Zombie_Template">
You made changes to the HealthMax settings.
<passive_effect name="HealthMax" operation="base_set" value="750"/>
3. Restarted the server/game for client host.