Repeating task not carrying over all sub-tasks

I have a daily recurring task set up that isn’t consistently carrying over all the tasks set up against it to the following day. I’ve learnt that if a sub-task isn’t completed in the current day, mark it as cancelled and then mark the main task as complete. This will then carry over the task and all eight sub-tasks to the following day and reset them all as incomplete, starting the process again. Perfect. A couple of times this week not all sub-tasks have carried over despite the above routine, today only three of the eight have. Because this is a recurring task, I’ve lost the other five tasks, so I can’t reallocate them to the main task, I have to create them again.