u/Key-Ad7820

I had a flight out of KJFK-KORD and for some reason when i was cruising through Lake Michigan, my flight plan just discontinued all future waypoints while i was still at WYNDE & 12 minutes out from GIBNS, so the first time I just closed the game out & rejoined the flight through AP+ & it happened again, so this time I waited to reach a VOR/DME station & clear my flight plan & just add a RWY10C APPR & it did the same thing. am I doing something wrong here? i swear i didn’t touched anything & my LNAV was still set to GPS & not NAV1