Ancestor Fallback - "Resetting" an ancestor field isn't clearing cache for tree in delivery node

[seankearney]

Environment consists of a CM and a CD instance.

Tree:

- a
    - b
        - c
    - d

Assume all items have the same template and a field Title is set at a to 'my-value'. b, c and d are all null.

If I change b's value to 'new-value' and publish, c shows the new value as expected in the CD instance. However, if I "reset" b's field (to null) and publish c is still shows 'my-value'