An error occurred when you tried to save the NPC in the prison in Fortress B1 on the Desert map. For some people, this went unnoticed because if you played with Kent (the starting character), it didn't affect you at all.

If the prison door has disappeared for you, update the game 0.71f or just download this file which will be available temporarily and replace it in the 'data' folder: 

https://www.mediafire.com/file/crq3rcok7ttrbsz/Map122.json/file

After updating the game, you will need to go back there to open the door and talk to the NPC.  This will happen for those who started the game by choosing Akua or Grace. For those who chose Kent (Fire) at the start, there will be no difference.

To get access to the eastern part of Metropolixxx (DLC / Patreon Version), you'll need to do this! Otherwise, you won't have access to the new content, the new areas and the new characters.