Programmatically enabling CC/Subtitles on full screen video (iOS) - Ionic app

I've got an Ionic app that uses webVTT files (chapter type) to track a users progress through a video. Works perfectly when the video is played in-line. Unfortunately when the video goes to full screen, the CC/subtitle setting is defaulted to off and I can no longer track viewing progress. Is there a setting I can where I can turn on CC/subtitles for full screen video? Do I need to write a plugin to change the setting? Any hints on where to start?