My experience with MobX has been the opposite.
I introduced MobX (along with HTML5 UI, React, TypeScript, etc) to a large team and it went swimmingly. Debugging/stepping-through was no more tedious than regular Chrome DevTools debugging.
I recommend using MobX’s strictest setting (where changing reactive objects can only occur in named actions), and restricting reactivity to a monolithic “model” (mdl) object and its children.
It really does make writing fast, correct & good UI a breeze, in my experience.