I have a seen a couple of posts in online forums where right before a P3 loses control and crashes, the video recorder shows the P3 going from P-GPS to ATTI and then it keeps cycling between the two very fast until the crash.

Yesterday before taking off for my ~40th flight, I performed pre-flight checks as usual. This time, when the app got connected to the P3 (while warming up), it kept going between P-GPS and ATTI super fast and I did not know what to do. I watch it do that for a few seconds and then decided to manually switch the remote to ATTI and then back to P-GPS and everything was back to normal. This happened before I took off. Luckily I was still on the ground and once the P3 finished "warming up", I took off and was able to fly 6000+ feet without any problems. That ist the furthest that I have been able to fly without any signal interruption.

Has this happened to anyone else? Like I stated before, I have only seen such behavior with the two P3s that lost control and crashed.

You observed an issue that you say yourself have read of instances where they crashed yet you still take the P3 6000 feet ballsy

probably just bad compass readings on the ground.