Last subtile remains on screen when playing remotely

When I play an .mkv file with the Android Channels client which has standard text subtitles remotely, the last displayed subtitle stays on the screen until the next one appears. So if there's a pause in speaking, the last subtitle remains on the screen until someone starts speaking again. It's like the client isn't honoring the length of time the subtitle should be displayed. This is on an Nvidia Shield.

This only happens when I play a file remotely. When I VPN into my home network and play it, the subtitle disappears once the line has finished being spoken.

Any idea why this happens?