Answer:
This is happening because the first step is the default in the post-processing mode but the last step is the default in the pre-processing mode. The load group is applied at the middle step of the CS3. Thus, it is shown in the pre-processing mode and not in the post-processing mode. In order to see the load group in the post-processing mode, you need to change the step to 'User step' or 'Last step' as shown below.