I was doing a flight from KLAX to KSFO. The ATC allowed me to "Resume Own Navigation" and then nothing. The ATC stopped talking and I found myself at 25000 feet above the airport. This happened to me even when the Control Tower gave me the heading. I needed to reset the IFR and everything went back to normal, however I needed to do this operation several times for it to work. I'm a Mac user and I bought xPlane 11 version 11.25. What should I do?