Bass only when I stand up…

I have the same issue without a solution except hanging the speakers for the celling to invert the problem.

I'm hoping someone somewhere has solved this.

Standing waves and null zones.  Only way to really solve is experiment with placement (speakers and listening position), and then augment with bass traps.  Analyzing using REW or the like will help in a more efficient journey towards a solution, as I wouldn't look forward to lugging those phenomenal speakers you have across the four corners of the room.

Speaker position is everything.  I have had this experience too.  The factors affecting the bass are distance from front wall, side walls and most importantly, distance between each speaker.  First, experiment by moving the speakers closer together in 3 inch steps.  When you hear a change go back and move them in finer increments.  Do the same procedure from the front wall.

As a rough generalization, very rough- the speakers want to be between 1.83-2.74 meters apart.  Sure, bigger speakers with big drivers can be further apart but in general 2.44 meters, plus/minus will be the sweet spot.  1 meter from the front wall minimum will help the bass and the soundstage.  Lastly, listening position is critical too.  Start with listening position equal to the distance between tweeters.  Then try moving back to 1.1-1.2 times the distance between tweeters.  Try to keep some distance from the back wall while moving those speakers away from the front wall as far as possible.

Bass traps in the corners will remove mudiness in the bass notes but they are not a cure for no bass. Ie. Bass traps don’t make more bass, they make the bass you have better.