Currently, when dragging-and-dropping an Element from the Add Element Panel, into the Navigator, there are two indicators that show where the Element will be placed:
1) A white line between Elements, showing where the new Element will go.
2) A border highlight on the Element that will become the Parent of the newly-introduced Element.

However, there are instances where these indicators display in the Navigator, but 'dropping' an Element in place will not succeed.

See attached video.

Repro Steps:

1) Create a Studio Project featuring a MainPage.xaml

2) Navigate to the Add Element Panel, and introduce a Grid Element into the root Grid of the Page.

Please be aware that pixel-perfect precision is required for the next step.

3) Drag another Grid Element from the Add Element Panel, and drop it in a position where:
a) The root Grid is highlighted.
b) The 'in-between' line is displayed between the root Grid and the Grid introduced in Step 2).
c) The top tip of the mouse cursor is to the left of the 'in-between' line's 'pointer' arrow.
(Please refer to the attached video for pixel position reference)

Observe how despite the 'in-between' line being displayed, and the root Grid being highlighted, the Element fails to make spawn in the Navigator.

Expected Results: If the 'in-between' line is displayed, and the placement target Element is being highlighted in the Navigator, a dropped Element, should place itself in the displayed position. We either need to adjust our tolerances of drop-zones, OR not display these drop-zone indicators if the target isn't valid.