If it's an LED, I suspect that it's just a bad light. LED's have tiny electronic circuits that reduce the voltage from 12v the RV supplies to 5v or 3v (depending on LED) that the LED requires. That little circuit is a switching power supply - it bascially turns the power on and off VERY FAST and what percentage of the time the power is "on" vs. what percentage it's "off" determines the power. But when those little circuits are bad, the result is frequently what you're seeing.
Nothing you can do to fix it short of just replacing the LED bulb.
Many of the early LED's out of China a few years ago had this problem - I'd see as much as 10% failure rate out of the box. LED's have gotten MUCH better in the last few years, but you still get a bad one occasionally.
Buddy Ray - Atlanta
Jayco 2016 Eagle HT 26.5RLS
Ford 2016 F150 Lariat, 3.5L V6 Ecoboost
Max Tow Pkg, 36gal tank
Reese Sidewinder and Reese Titan 16k hitch