I am glad I found this thread. My 2018 Pacifica Limited also exhibit the list GPS signal issue. I only noticed it after the clock started being off by 3 minutes and then did not switch to DST. I stopped using the build-in NAV in favor of CarPlay a while ago so I had not even realized that my NAV had quit working. Software Update for Uconnect® - Check For Updates says the vehicle has the latest s/w. From the posts here is seems pm-ing @ChryslerCares is the best path forward. So, I do this next.