iOS 12, beta 3. Had same issue with beta 2.
iPhone X
GPS not working in all navigation apps. Noticed that in Apple Maps, the orientation never changes. Always has North facing up. On a hunch, I checked out Compass. And same thing, you cannot recalibrate it.
I've already reset network settings and toggled location services, and reset location and privacy to no avail.
Anyone have a solution for this?