At "The Lost Expeditions Prototype Lab" mission Far Cry 3, when I found 3 documents, didn't show me this "letters of the lost lab" (password: 122112, and still show me 2/3 documents found! and didn't show notice "Find a way to exit Lab", so can not exit lab never!

I mean minute 07:41 of this gameplay:
https://youtu.be/V3i1QssnQys?t=461

And when use restart mission, I back at same mission, and my game is locked in here!

Strange point is when suicide and die, show me this letter and back to from start mission!

I thinks it's a bug.
I play in PC

Can you help me?!