RTK GPS status icon

Hi.
I use Pixhawk and PX4.
I running RTK-GPS using C94 M8p.
While RTK is running, no RTK-GPS status icons are displayed in my QGC.
After several tens of minutes, the GPS lock suddenly changes from 3 to 5 (float-rtk).
Why?

I updated the QGC version to the latest, and this problem was solved.