Incomplete database update: the real estate information database does not contain the information of public houses in 1986, or the information is not updated to the database in time. Ask a real estate agent or lawyer to help you inquire about relevant information. They may have more resources and experience to obtain real estate information.
Transfer or reconstruction of public housing: 86-year-old public housing may have been transferred or reconstructed, resulting in the invalidation or inapplicability of the original property right information. If there is no electronic record of public housing information, you can try to consult local paper files, such as the archives of real estate archives or relevant departments.