This is a part of T61296: Crash with animated b-bone segments. Consider animated/driven bendy bones segments as something what requires special bendy-bones operation and relation in the dependency graph. This is because it is more beneficial from a performance point of view to not build operations if they are not needed. But if the property is animated it is not possible to make any reliable decision based on just a property value. Differential Revision: https://developer.blender.org/D4739