I teach a Lightroom course in the winter. The issues with LR 6.0 and now 6.2 and 6.2.1 are making me consider dropping the class. I can't work with technically challenged students with such a complex program that has so many bugs. Right now, on my own computer, I find the software almost unusable.
Many issues are easily fixed, but since you don't state the specific issues you are having, we would need to know in order to tell you how to fix it.
Right now, see my post under Slideshow Crashes. Two problems: Slideshow crashes lightroom, and Lightroom is eating my CPU while doing nothing obvious.