This is not a bug, but intentional. Kamau is described as a "shy baker," which, in my opinion, is reflected very aptly in the implementation. Ultimately, it is quite simple, Kamau and his bakery only become accessible once you have accumulated the necessary points to increase his Bound level. From Bound Level 3 onwards, Kamau and his bakery remain permanently available, and you can enter them at any time.
Well, one could have a discussion about whether the game really has an end, but oh well. Okay, if you have the maximum bond level with all characters, then yes. However, if the bakery doesn't appear for you, strictly speaking, you can't have actually finished the game. As I said, I hope I was still able to help you.
