It is difficult to determine the exact mindset of individuals who greet others but then ignore them in public. However, it could be due to a number of reasons such as insecurity, feeling threatened, or simply a lack of social skills. As an HR expert, it is important to address this behavior in a professional manner, perhaps by organizing team-building exercises, providing training on effective communication, or having a one-on-one conversation with the individual(s) exhibiting this behavior. It is important for all employees to feel valued and respected in the workplace, as it can have a significant impact on their productivity and job satisfaction.