Inconsistent/flickering light - INFORCE Gen3 APL Glock Weapon Light, 400 Lumens

I’ve owned this light for 2 years. Used it on my glock 19X with the Trex arms Ragnarok holster. When I press the paddle to activate the light it will sometimes not come turn on at all. If it does turn on it flickers on and off as I run, change shooting positions (even as simple as stationary target acquisition rotating from the hips and/or shoulders will cause the light to flicker or turn off).

I have used the streamlight and surefire batteries and nothing seems to make it work.