It’s probably just a huge adjustment. He’s never without you, so imagine how scary that is. It can take time for sure. But this is also the age of separation anxiety!
My baby did this for a while. She was younger though. I talked to the care workers and they suggested coming more. Even if it’s not for very long just to practice. I also think it helps my daughter now that’s she bigger when I show her / tell her explicitly where I am going to be. Obviously she doesn’t really get it but it seems to help
What happens after you leave?