There are multiple reasons why your task might be empty. The most common problems are:
You have no widgets added to your task. In this case, you first need to Enableedit-mode . Read more about how to do that here. Be aware though, that you might not have permissions to do it (i.e. you are not the manager of the respective project). In this case, the Enableedit-mode button will not be visible at all. Contact the managers of the project in order to have your task configured as desired.
You have selected one or more part models , but neither of the part models has part instances. This will happen if the quantity is set to '0 or 1' or '0 or more' and no parts have been added in the product. Read more about it here.