Can you tell whether this is when the month has 31 days? From memory somewhere back in the dawn of time I think the census point is 30th day of the month, so if their start date is 31st, it won’t pay you for that first month.
This is all to do with how the number of months is calculated and when payments are made. The last day in each month is the date that triggers payment, it used to be called the census date, that is where the learner is in learning on the last day in a month then payment is triggered.
Nothing to do with the 30th day of the month.