Javascript not showing for no reason

On my background video, I have a mute/unmute button that is supposed to show (using JS video player Plyr). It shows fine on a test site I created, yet on my client’s site where I need to use the video, it just refuses to show.

I’ve tried deleting all other custom code and it doesn’t help. The answer must be simple but I can’t seem to find out why it isn’t working? Any help from custom code wizards is greatly appreciated

Test site where it works:
Client site where it doesn’t work:

Hi @Forbes,

I’ve recorded a quick video showing you what I’m seeing in DevTools to hopefully point you in the right direction. You can watch this video here:

Hope this helps!