Cult of the Lamb missing general building after maxing out everything else
I've levelled up everything but I have no idea how to unlock this final general building.
It's The Grave missing in your buildings. It can be unlocked in the Level 4 Afterlife Doctrine by choosing "Grieve the Fallen".
If you instead chose "Return to the Earth", it unlocks the Natural Burial building. So, you cannot unlock all buildings in a playthrough.