I use the first two encoders on the top left the most for Exposure / Temperature & Tint.    
If I rotate the dial slowly it works fairly well, but if I want to make a big change by rotating quickly it doesn't register all that well or if at all.   At first I though it was Midi2LR / LR that was jumpy for exposure, but then noticed that wasn't the case at all.  I assigned a different encoder for exposure and it's smooth.   I also did a hard reset, but that didn't help.
I love the X-Touch mini but not so sure if I would replace it with another one if the same thing is going to happen.   
I haven't had it all that long.   I'm guessing they are using cheap encoders?