Copter don't go to 2nd WP after takeoff (AUTO MODE)

Hello, i’m flying a heavy lift hexacopter with black cube and arducopter 4.0.7 for more than 6 months, and today I had the same problem as I did before.

The copter engage auto mission, takeoff and climb do desired height but, it doesn’t go to the first waypoint to start the mission, it keeps hovering on takeoff position so I have to engage loiter and land.

The weird thing is, I did a sucessful flight and right before that, and then the problems appears, I’ve tryied modify the takeoff alt, do the first succesful mission again, but without lucky.

My solution for the first time was formating the FC and did all configurations again.

But as Happen twice, maybe its time to seek the problem.

I will upload logs and tlog with first succesful mission and the other trys with problem:

https://drive.google.com/drive/folders/1wnnGt3uBOhxuasIuLWmNfju1bxaffDWQ?usp=sharing

UPDATE: Later in the morning I took another drone (exacly same specs) and did the same missions (exacly the same files) with success!

UPDATE 2: This problems seens to be very old, I’ve found other posts dated 2017 with same problem but without solution. This link has other 3 links with same problem: https://github.com/ArduPilot/ardupilot/issues/15070

IMPORTANT UPDATE: I’ve found something weird, the param WPNAV_RADIUS was 0 in both case when I had problem, its weird becouse, everytime that I build a copter I set this param to 500cm, but in both case this param changed alone. I will try set 0 again and see if the problem appears and then change to 500 again to check if the problem is solved.

I’ve Checked my last success mission and WPNAV_RADIUS was 100cm and now it is 0cm, maybe this really is the problem.

PROBLEM FOUND: I don’t know why, my FC has changed the param WPNAV_RADIUS to 0 in both time, this value can’t be zero it has to be between 5 to 1000cm, this way the copter cant reach the waypoint and to to second WP.

Today I did the test, setted it to 100 and it flew percetly and using the same mission I changed to zero and the same problem happen, got back to 100 and flew ok again without changing mission.

Now the problem is, Why my FC is chaging the params by it self and how to avoid this to never happen again?

Can you send the waypoint file as well?

Sorry, I don’t have it now. But as I said, I tryed to use the first mission, which flew well right after the propem appers, without success.

Later in the morning I took another drone (exacly same specs) and did the same missions (exacly the same files) with success!