This fix is for people who do monthly rents.
When a tenant moved in part way through the month, the first months rent is calculated as a percentage of the normal rent based on the number of days the tenant will be occupying the property. However this rent calculation was not correct when the move in date is a month with only 30 days. Months with 31 days were correct.
The rent split calculator found under the general menu group has always had the correct values.