Hi,
I have the same problem, but I found a solution given by @RdLr in the gitlab that works for me 
Hi @aibd, I can confirm your observations. A workaround for me was to toggle the “Use WiFi” switch of the “Mozilla UnifiedNlp Backend” configuration in MicroG to “off” and then “on” again (while the wheel was spinning in the mapbox sub-window). This resolved the issue for a single turnaround from “random” to “real”. The next days I’ll try to build v1.1-r for comparison. Maybe things are better then. I’ll tell)
Surprisingly, the GPS works normally on the maps application or on an F-Droid application (GPS cockpit), but does not work on Transportr or on GMaps WV. I initially thought it was due to mapbox and advanced privacy but even after fixing the mapbox problem these two apps (Transpotr and GMaps WV) still don’t work.
Moreover if I activate GPS spoofing, in this case Transpotr and GMaps WV give the spoofing position like on mapbox.
I don’t understand why my GPS works with some apps and not with others when the same permissions are given.
EDIT : My phone : Samsung galaxy S9 dev build v1.1.