Greetings…Not to worry, I will definitely help you out and get this working for you. The one thing I need to know though is what sidebar position is the widget in that you are trying to change the hover colour for the links?
….what I will do is try this on my local test site and see if it’s a bug in the code, but to also find a solution for you.
Oh, also, what widget is it?
I’m about to call it a night here where I am, but I’m going to take a guess at a possible solution for you. Add this to the Additional CSS tab in the customizer and then add your colour value to it.
#left-sidebar a:hover,
#right-sidebar a:hover {
color: #000;
}