Can say as I have noticed that. If I am in an area with poor gps I will take off and climb to about 20M and I soon pick up plenty of satellites, I reset home position then upload the mission.
I've had mine take a long time to get satellites and other times, it was quick.
Depends on where you are, the clouds around, and how many satellites are above.
I've had as many as 13. And there are 24 worldwide?