Did you set the minimum level (Parameter 5) to the appropriate value for your LED bulb? They vary from brand to brand and model to model. Some of mine are at 40. This means that my bulbs do not show any visible light until the dimmer is at 40% of output. In a 3 second ramp rate, that’s more than a second before the LED had enough power to
Light. By changing the minimum power level, it makes it so the usable curve is adjusted so it lights immediately so in reality a 1% Dim value is worth .6% of the usable light output range of on a perfect curve (which it is not). You can find your minimum level by starting dimming below the light output until the unit lights. I have found that LED’s typically will go lower than the minimum level on a ramp down (below the minimum level) but will not light on a ramp up at that level. That’s also likely why your ramp downs appear fine.
-Travis