QuickTime intermittently disables audio and subtitle menus for MP4 asset with multiple tracks

I packaged an MP4 video using FFmpeg. Video contains multiple audio and subtitle tracks. The audio and subtitles options are verified selectable in Safari and VLC viewers. In QuickTime 10.5 on my mac (Sequoia), the audio and subtitle menus are intermitantly disabled on this same video. I found that exiting QuickTime and relaunching the video in QuickTime from Finder seems to reset QuickTime so it would now show the audio and subtitle menus.

Any thoughts on what may be contributing to the observed behavior in QuickTime? Is there a best practices guideline available for packaging MP4 to ensure quicktime ALWAYS enables the language options? Thanks in advance.

[Re-Titled by Moderator]

Original Title: QuickTime disabling Audio and Subtitles menu for MP4 asset w/ audio and subtitle options available in Safari.