I have never had a problem with concrete or a landing pad. Now and again I get a compass error, although this seems to happen at random. Most times, I just ignore the error and once the drone is in the air it seems to go. I don't seem to have ever had a problem with the compass in flight.
When I had a Phantom 3, that would often take a while to get it's GPS lock on the ground, but again take off and hover for a few seconds nearly always got the position very quickly. I don't think that the GPS was as good on the P3 Standard as other newer drones.