I updated my CubeOrange from ArduPlane 4.1.7 to 4.2.1 and GPS here 3 just stopped to working
In 4.1.7, at the same position (inside office), gps locked with 3 sats and I received data (GPS 3D FIX)
After updating, the number of sats stay at one and I waited a long time.
Already started a discussion in Ardupilot forum and I was told that it is ok, and suggested to look for information here.
The logs are attached, from a flight in 4.1.7 and an update to 4.1.2