I am trying to apply an update to this macOS Catalina Security Update 2021-008 10.15.7 but it says that I must restart to install but it just restarts and no update has been done. This is a fresh instal from a bootable installer that I made quite a while ago but I have never had trouble doing all the required updates before on a multitude of machines (it's currently on 10.15.7) Any ideas please? Thanks