Currently, creating a Template from a Horizontally-oriented Slider works as expected.
However, if 'Create a Template' is performed from a Default Slider that has been set to the Vertical Orientation, upon creating the Template, the Slider will completely cease to function.

Repro Steps:

1) Create a Project containing a MainPage.xaml
2) Introduce two Slider Elements to the Page, and set one to a Horizontal Orientation, and one to a Vertical Orientation.

3) Right-Click on the Slider in the Horizontal Orientation, and from the 'Templates' context menu, select 'Create', and store it wherever desired.
This will open the Template up in the Template Dummy Editor.
4) Exit the Template Dummy Editor, Play the Page, and click-and drag the Slider Thumb left-to-right.
Observe it functioning as expected.

5) Right-Click on the Slider in the Vertical Orientation, and from the 'Templates' context menu, select 'Create', and store it wherever desired.
This will open the Template up in the Template Dummy Editor.
4) Exit the Template Dummy Editor, Play the Page, and click-and drag the Vertically-Orientated Slider Thumb top-to-bottom.
Observe that the Slider has lost all functionality.

Expected Results: If creating a Template from a Horizontally-Oriented slider conserves its functionality, so too should a Vertically-orientated one.