If you have Quiet as a buddy on certain mission, you’ll stop progressing through the story.
If you’ve grown attached to Metal Gear Solid 5: The Phantom Pain’s Quiet and having her along as a buddy on missions (and why not? She’s a fantastic sniper) then you may want to consider a short separation. Konami (via NeoGAF) has revealed that game progress can be stopped if you have Quiet along with you on certain missions.
According to Konami, “there is a possibility that the game stops progress if having Quiet as a buddy while playing ‘Mission 29’ or ‘Mission 42’. This situation can be avoided by not using Quiet as a buddy while playing either ‘Mission 29’ or ‘Mission 42’.”
Konami apologized for the issue and promised further announcements on its resolution. As it stands, the bug affects all platforms so if you’ve noticed a lack of progress when having Quiet on these missions, this is the reason why. Stay tuned for more information on future fixes – hopefully Konami can resolve this fairly quickly.