When you pass doctrine proxy object to twig render function e.g.

{{ render(controller('ExampleBundle:Example:index', {'item', md.item})) }}

where "md" is entity with property "item" that represent object of many to one relationship, render function converts proxy object to array and "indexAction" of "ExampleController" gets that array instead of proxy object and you lose all access to getters and setters.

See this issue #7122;