PC not recognizing Arduino when working with a class and MIDIUSB library
You need to take care with constructors in C++.  They get called during the global variable initialisation phase of the execution, which happens before main() gets called.

main() calls the routines that initialise and configure the peripherals and such in the chip, and by having analogRead() in your constructor (which is itself another error I will mention below) there is a good chance (I don't know the full initialisation sequence of that chip though) that it will never complete, and thus your program hangs at that point.

Your analogRead() doesn't want to be in the constructor, anyway, since that will only execute once when the object is constructed.  Instead you want to have analogRead() called at the point you need to get the analog value. In your code that would be at the start of int Pot::getValue().