Have you tried stretching your lats in every way possible? Are you self-mobilizing your shoulders incessantly with monsterbands? Chances are you are neglecting a HUGE aspect of increasing range of motion - learning to actually USE it.
If you stretch, stretch, and stretch, you'll gain some flexibility. But that mobility is often only temporary. In order to make lasting gains in mobility, you first need to learn HOW to use your new range and THEN load it! This video shows one of my favorite drills following any sort of lat stretching to really solidify mobility gains.
Using a foam roller, really sink into your chest. This will open up the chest and increase the amount of flexion at the shoulder.
Rotate your hand out, into external rotation, as you roll out. This will preferentially bias stretching the lats, as they perform internal rotation.
Hold this position for a few seconds, then try and lift your hand OFF the foam roller for few seconds. A good cue to use for this is to "put your scapula in your back pocket" to facilitate the lower traps and posterior tilt of the scapula. If you can't lift your hand, don’t worry! The goal is to ACTIVATE your scapular muscles at end range and learn to CONTROL the movement.
Shoot for 10-15 reps of this exercise. After that, LOAD IT! Overhead press, overhead carries, snatches - whatever movement you want to improve!