This link is a screen grab showing a portion of my task list.
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As shown, I'm filtering to show only deferred tasks. Yet several tasks near the top clearly do not fall into the "deferred" category. See that "status" column near the right side of the picture.
This filter only shows and hides deferred task, it does not isolate them from the other statuses. You can view only the deferred task by clicking on the status view in the left side menu, then clicking on the "deferred" option. I hope this helps.