time-grid should not consume all items in list of TODO entries

First of all, thank you so much for super-agenda :heart:

I encounter unexpected behavior where I am not sure whether it is the intended way.

When I open the "List of all TODO entries" (`t`),
all my items are under the `time-grid` group,
even though there is no time grid in the TODO list.

I would expect the `time-grid` group to be empty and all tasks to be passed to the next group.

My config:

```elisp
(setq org-super-agenda-groups
'((:name "Today"
:time-grid t)
(:name "Foo"
:tag "foo")
(:name "Bar"
:tag "bar")))
```

When I `M-x org-agenda` -> `t`, _all_ my tasks are listed under `Today` instead of `Foo`, `Bar`, and `Other`. Am I misunderstanding something here?