Currently in the Navigator Panel, it is possible to perform two different multi-selection actions:
1) Holding Ctrl and clicking on Elements, selects the clicked elements in a multi-selection.
2) Holding Shift and clicking between two elements, selects both Elements, and all Elements in between them in the hierarchy.
These are both correct, and expected behviours.

However, in the context of the Storyboard/Timeline, this functions differently:
1) Holding Ctrl and clicking on Elements, does not allow multi-selection
2) Holding Shift and clicking between two elements, selects both Elements, and all Elements in between them in the hierarchy.
Additionally, if a Shift+Click action is performed to select the entire range of Elements in the Timeline, they cannot be deselected without clicking on any layer in the Navigator

Additionally, if all layers in the Timeline are selected, and any one of them has their expander selected in the Timeline, it will result in creating multiple 'Hover' states for Timeline Elements (The expanded one, and the actually-hovered one)

Additionally, if multiple layers are multi-selected in the Navigator, only one of them is selected in the Timeline.

Video Attached.

Repro Steps:

1) Open the Z3L_LiveDemo Project from the GitHub InternalProjects repo.
2) Enter one of the Templates for one of the Buttons on the left of the screen, and navigate to the Animation Panel.

3) Within the Storyboards Tab, select 'VisualStates', and select the 'MouseOver' VisualState from the list. This will expose its Timeline.

4) Hold Ctrl, and click on multiple layers in the Timeline to attempt to select multiple Elements at once.
Observe how multi-selection in the timeline using Ctrl+Click cannot be performed.

5) Hold Shift, and select the top-most Element in the Timeline, and with Shift still held, select the bottom-most Element in the Timeline.
Observe how all layers in the Timeline are successfully selected.

6) Attempt to exit the multi-selection by Clicking, Ctrl+Clicking, or Shift-Clicking on any of the Timeline layers.
Observe how the layers can not have their selection removed.

7) Whilst still in this state, click on the arrow to the left of any of the Timeline elements, and move the mouse up and down through the items in the timeline (hovering over their names).
Observe how the bright blue backer usually reserved for 'hovered' items is present on multiple layers at once.

8) Select any Element in the Navigator to remove the selection from all items in the Timeline.

9) Use Ctrl+Click to multi-select any two Elements in the Navigator that also appear in the Timeline.
Observe how only one of the many Elements selected in the Navigator is also selected in the Timeline.

Expected Results: Selections and Multi-Selections within the Timeline follow the same rules as those observed by Elements in the Navigator, and the selections across both panels mirror each other.