Why can't I move in when I buy a new house?

I am a foreigner. I bought a set of 100 square meters of commercial housing a few years ago, and the procedures for house purchase and transfer were very smooth. The real estate certificate and the land certificate are both my own names. I haven't checked in yet because I'm too busy. Until recently, when Chen Xiao came to the police station where his household registration was located with all the house purchase procedures, the staff told him that his household registration would not be moved until five years later, so Chen Xiao's whole family was dumbfounded. Why can't they understand that the procedures for buying a second-hand house are complete? Xiao Chen said that he bought this house for hukou, and he wanted to settle down. In the future, personal insurance and children's schooling are closely related to household registration. Now he doesn't know what to do with such a result. It is understood that the reason why Xiao Chen's hukou can't be moved in is because the previous householder is also a foreigner. According to the staff, there are local regulations for the migration of foreign accounts. For foreigners who buy second-hand houses, if the former head of household is also a foreigner, and the household registration will be moved into this house, then the buyers of second-hand houses will have to wait until five years after the former head of household moved out to register in registered permanent residence. Xiao Chen felt very helpless. He said that he didn't know that the previous owner was also a foreigner, and he didn't know that the government had such regulations. This house was bought by Xiao Chen through an intermediary company, and neither the intermediary company nor the former head of household knew about it at the time of purchase. Xiao Chen said that he had expected this house to help him solve the hukou problem, but now, the insurance can't be done, and the children will go to school in the second half of the year, waiting for the hukou to go through the entrance formalities. Regarding the situation in Xiao Chen, the relevant police said that the issue of household registration is a mandatory regulation issued by the government. Xiao Chen can go to the police station with the purchase contract and personal ID card to check the time of the last householder, so as to determine when he can move in. The insiders believe that when foreigners buy a house for the purpose of moving in, they must first understand the detailed household registration policy of the place where the household registration is moved; Secondly, if the purchased property belongs to the second-hand house, you must know clearly the household registration status of the owner before buying a house, whether it is suitable for you to move into the household registration, and then consider buying a house, otherwise you will not be able to go through the household registration procedures in the short term.