Ya..they found them...after they had been copied.
Someone accidently put top-secret hard drives behind a copy machine...but nobody found them the first 4 times they searched.
If you remember, there was a fire that caused an evacuation of the facility and it was only due to that evacuation that the drives were discovered to be missing. They were supposed to be in a safe that had red-chinese walking in and out of it daily with the other "scientists" in the lab smiling and waving as they did so.
Can you say "Clinton Era"??
So when you said missing, you were ... wrong.