Spoke to Samsung again today and yes, have heard of the issue! Why are Samsung not commenting on this on the members forums at least? A message to simply say that we are aware of this problem and working on a fix would reinstate some respect in Samsung . Instead the customer is being COMPLETELY IGNORED!
They said "When our experts checked the log, recording worked immediately after restarting. After rebooting the phone, several apps were operating in the background, so there is a load. For stabilisation, please check after 5 minutes of restarting your S23 Ultra. If the same problem occurs, please attach the log and video at the time of occurrence."
They just don't care. Because this never happened on my s21 ultra.