Precision landing does not work

We have worked on precision landing companion computer and it used to work. we had some changes in body structure and we’ve tried it again, first we had target acquired but copter does not follow the landing pad, after a while there is no target acquired in logs either!
we’ve checked range finder and it is working properly. and also we opened propellers and armed the copter, while it had been armed we lifted it over the landing pad and there was target acquired in logs.
there are logs of two tests, any idea? (767.7 KB)