I just checked out your save file. Thank you very much for uploading it here 
The baby still is part of the world → Zoi ID is working
Common methods to move any Zois when bugged don’t work at all → does not respond in any way
Even deeper building levels like platforms don’t move the baby → I assume it’s stuck due to its life stage (not able to move on its own) and a wall / floor glitch with similarities to My zoi got trapped in the wall, died and was resurrected & Zois trapped/stuck also in other places of the world
I even did a manual reset of the properties in this world and tried the emergency rescue several times but nothing changed. The baby Zoi remains stuck in the floor. Interactions from the adult Zoi (only 1 interaction available) don’t work. They cancel them autonomously.