Hidden objective in the "A Hero's Way" mission

A hidden 6th objective appears in the mission "A Hero's Way" after interrogating the target several times.

The objective itself is generated following the interrogation, where the commander states "There's something hidden...", to which an empty objective will appear on the iDroid mission tab.

As you complete other objectives, the game will still say that you've completed objective number x out of 5, rather than out of 6. At the time of writing, there have been no reports of completion of this hidden 6th objective. Most dismiss it as a possible bug.

Interestingly, the objective will not appear if you have already completed all of the objectives previously.

This mission may tie in to the possible P.T. Connections due to being the last mission in the string of missions "20 48 6 3" sequence, where the others contain PT Radios or radio broadcasts.