Hi @Kemper, thanks for your advice. I had a couple more test flights today and apparently I am being able to workaround this focus issue. Both times I took off with DJI GO 4 to the target altitude (DD was enabled to manual focus), manually focused and switched to MF, changed app to DD and started the mission. I did not disconnect the RC cable when changing apps.
The first flight was OK, DD took control correctly of the flight.
But on the second flight, DD did not manage to take control of the drone without disconnecting the RC cable. The problem is that, as soon as I disconnected it, the drone started landing. I could only manage to correctly set the second flight after shutting everything off and turning on again.
@Jamespipe, thanks for the workaround! I will try to test it soon and I will let you know.