Meta Software Developer interview questions

It took me 1 phone interview followed up with 2 onsite interview. First onsite interview has 5 interview sessions and second has 2 sessions. The interview went good, and interviewers are nice. And I answered all the questions fluently and definitely sure that most of interviewers feel love to talk with me. Since two interviewers mentioned how would I expected for new hire camp and another one worked me to the patio on top of the building. But the strange thing is that the recruiters get totally silent after that although I sent 3 emails out after last onsite interview until one day they called me when I was driving without notice after hour and said I was not selected. I asked for the reason and what part I can improve, and they just said there is no reason and everything is good, and team is impressed by me, and it is just a hard decision. A week later I learned FB employee suicide event and it makes sense to me that why FB made the decision because they just has issues inside without let people know, and best luck for the software engineers in FB!