We discovered that our patch v1.005 on December 1st introduced a pretty serious bug that caused many doors in the game to save as "Opened" whenever the level was reloaded after reaching a save point.
The bug has been fixed but if you are already part way through a level those doors could still be missing. You should be able to finish and the next level will be back to normal.
If you got stuck in the maze in Nyvena because of this bug, the Red Door will unlock itself after 1.5 seconds.
Its possible that you have experienced this bug without noticing, and it's also possible that you played through without actually being affected by the bug because it is limited to certain areas and circumstances.
If your save data gets you stuck anywhere in the game, don't start over! Please let us know and we'll get it fixed as quickly as possible.
Thanks for your patience!!