Repro Steps:

1) Create a Page
2) Create a Grid Element set to Horizontal and Vertical Alignment 'Center'
2) Create a TextBlock in a Font that has an Oblique (/Italics) option. (My issue occured with Libre Bodoni if you want to repro: https://fonts.google.com/specimen/Libre+Bodoni )
3) Type a string that ends with an 'f'. The Oblique-ness of the character should push it outside of the bounding box
Observe how the 'f' character render slightly outside of the Grid's bounding box, but is fully visible.
4) Animate the TextBlock along the Y-Axis (if your text is horizontal)
Observe how the 'f' character is clipped until it reaches its final position and the animation terminates.