I have been falsely accused of bullying by an employee who is clearly using this to hide poor performance and uncompleted work, all of which can be evidenced. all my communications have been professional and offering support. However, when I ask the employee to evaluate their approach to any project work, the employee cries bullying. I have asked the employee to escalate their concern of my bullying then the claim stops. I have volunteered the detail of the accusation to my line manager who doesn't want to investigate the matter in fear it will reflect poorly on him. Although I want to support my employee, this recurring culture of making accusations is unacceptable and I would like to stop it. Any guidance would be appreciated.