Orator highlighting leaving artifacts in Edge

The Orator leaves graphical artifacts leftover from highlighting as it progresses through a body of text in MS Edge 44. The bulk of the highlighting is removed, but small elements here and there persist.

To reproduce:

• navigate to the Orator demo page: https://build.fluidproject.org/infusion/demos/orator/
• press the Play button to begin playback

Expected:
The highlighting will follow along with what is being read, and will be fully removed from words after they are done being read

Actual:
Parts of the highlighting (most often the top and left sides) will remain after the word has finished being read aloud. See attached screenshots for examples