I've had new LED downlights installed with dimmers by an electrician. They're mostly fine and they were the recommended dimmers for the LED lights from the shop that I purchased it from.
The issue is when I dim the lights to about 1/4 brightness, the LED lights turn off in some of the rooms. In other rooms turning the dimmer all the way down doesn't turn the light off and just creates a dim light.
Is this something that's adjustable on the dimmer or did the electrician mess something up?
Many, but probably not all, dimmers will come with an adjustment to set the "minimum" dimming level. Simply remove the cover plate from the outlets (safe to do with the power on, just don't stick your screwdriver past the face of the switches and poke around in the back of the box) and you should see a (very) little lever or perhaps a plastic screw that will probably have a "+" and "-" markings on it. Using a small screwdriver, move the lever/screw one way or the other until it's where you want it.
I installed 3 identical (same brand & model) dimmer switches for 3 ceiling fans in my house. One of them gives a very soft glow when the dimmer is all the way down. The other two turn the light off at some point before the dimmer is all the way down. I need to adjust those two, I just haven't gotten to it. :(
