Hi, I playing with Wife Co-Op mode too and we encountered same problem. We playing with some mods and Yesterday night before my logoff i saw her character - she hosting the game. And today we started as usual and she invited me via friend list and BAM i can’t see her character.
We fixed it just by loaded backup save from yesterday. All is working but everything from today is lost.
What i discovered is that save file from night have about 1,5MB and corrupted saves where i stopped to see her have 5,9MB but we didnt build much more for increase file size so much…
Edit: It happened again. We playing Siptah map. I was disconnected from co-op and then after reconnect same situation.
Edit2: Loaded another backup. We tried to disable Shani’s stuff mod and load one backup few minutes before disconnect and… Its working. Do you guys using/used this mod in co-op?