What is this bug? Should I be worried?
There is a bug that's verified to occur in the Pressure Exchange (PEC) puzzle room and Crew's Quarters puzzle room. If you save while in this room, the game will crash and corrupt the save data. You will have to delete the save and start over. EDIT: (or possibly in other puzzle rooms, the PEC and Crew's Quarters rooms are the biggest known culprit at this time)
Yikes! Will this be fixed in the future ala patch?
No information is available at this time. We can only hope a patch is possible.
What if I save in a different slot?
Unfortunately the 3DS version of the game only has one save slot.
So if the game crashes, my save is nuked?
Only if it crashes when you save in the PEC puzzle room or Crew's Quarter's puzzle room EDIT:(or possibly in other puzzle rooms, the PEC and Crew's Quarters rooms are the biggest known culprit at this time). Other crashes have occurred that don't involve saving where the save is unharmed.
Does this bug affect the Vita version as well?
No, it does not. No bugs of this nature have been reported regarding the Vita edition of Zero Escape: Virtue's Last Reward.
I've already bought it on 3DS! How do I avoid wrecking my save file?
Do not save in the PEC room puzzle! Better yet, just don't save in any puzzle room at all.. The game may still crash, but so long as you save before you start that room and not during the puzzle, your save file should remain intact.
Does this bug occur in other puzzle rooms?
Unconfirmed, but better to be safe than sorry. You might want to refrain from saving your game during any Puzzle room segments and only save during Novel segments.
EDIT: for those who want to know when they're headed toward the PEC room.
For those wondering, the PEC room is in the middle branch. More specifically, the route that takes you to it is:
Yellow door -> Ally -> Blue door
AHH! My game crashed and I didn't save in the puzzle room!! Is my save gone?
See this post. Your game may crash, but that doesn't necessarily mean the save is corrupted. You'll have to check by trying to load it.
OP should be edited.
Do not save at PEC room AT ALL, puzzle or novel segment.
The best solution to avoid this bug is saving at corridors and warehouses, never save inside a puzzle room. NEVER.