Greetings @defaultbhk9lownmj8c and anyone else browsing this topic. Thank you for working with me directly on this. We know what the problem is now. Under the Sequence menu, find "Sequence Follows Playhead" and make sure that is unchecked. Now use Ctrl/Cmd + M or choose File > Export Media and it should work regardless of which Export Settings you use.

Huge thank you to my colleague @270120 who helped me figure out this simple but hard to find workaround. We have an internal bug in place to fix the root problem as well.