title: Ml-agents cooperative push block not returning rewards
body: <p>I'm working with the <strong>Cooperative</strong> push block environment ( <a href="https://github.com/Unity-Technologi...nvironment-Examples.md#cooperative-push-block" rel="nofollow noreferrer">https://github.com/Unity-Technologi...nvironment-Examples.md#cooperative-push-block</a>) (exported in order to use the Python API) using the latest stable version. The issue is that I'm not getting the reward (positives or negatives). It is always 0. If I export the <strong>Single</strong> push block environment, I receive the rewards correctly. Below you have the code I'm using from the collab example <a href="https://github.com/Unity-Technologies/ml-agents/blob/main/docs/Python-API.md" rel="nofollow noreferrer">https://github.com/Unity-Technologies/ml-agents/blob/main/docs/Python-API.md</a></p>
  <pre><code>decision_steps, terminal_steps = env.get_steps(behavior_name)
  if tracked_agent in decision_steps:
      episode_rewards += decision_steps[tracked_agent].reward
  
  print('REWARD', decision_steps.reward) # Always 0
  # Each decision_steps[tracked_agent].reward also returns 0
  </code></pre>
  <p>I should receive a negative penalty (-0.0001) or a positive signal +1, +2, +3 as per the docs. Even if they randomly push a block, I receive 0 as reward.</p>
  <p>They say in the docs that the reward is given as a &quot;<strong>Group reward</strong>&quot;. I don't know if that implies a change in the above code.</p>