Is it all phasing or is it something more?

Speakers are definitely in phase as this is the only content that I notice it on plus I hear the same issue on my girlfriend’s system. Still wondering if it reproduces on non-streamed DVD or Blu-ray media. 

I have several CDs with one or two tracks recorded out of phase. This is a technical mistake, and easily corrected changing the phase of one channel. However, I have also heard some New Age music and some instruments were recorded out of phase to give an ambient effect. It also prevents you from localizing the instrument.

You can take a 30 sec long segment of the audio and change the phase of one channel to see if it improves the sound.

There was an article in the NY Times recently discussing why over 60% of Netflix viewers use closed caption sub titles- it's due to the combination of too many loud sound effects over powering the dialog, a trend for actors to be whispering / speaking at low levels for "dramatic effect" and lastly that many movies are of course mixed for surround sound and increasingly for Atmos - so the downmix for TV audio is compromised. I don't think playing with a phase switch will do much for you.

Previous responses have hinted at this but didn't quite get there. Stream the movie again and wire your speakers out of phase and see what happens. It sounds like the stereo soundtrack may be out of phase and it is easy to test this.