My 2018 Lincoln Navigator Select has issues with the power liftgate on occasion. Sometimes I am unable to open or close the liftgate by pressing the buttons on the key fob, the open/close button on the liftgate or the button inside the vehicle to the left of the steering wheel. Has anyone come across this problem before? Any solutions? It doesn't happen all the time, and can get to work again some times after waiting a little while, or restarting the engine. TY