The Time Off Details report for individual employees has as the first line "Current balance". The balance per accrual type is only showing the difference between what accrued thisyear and used thisyear. It is not taking into consideration what has rolled forward from prior year.
In the attached you will see the employee started the year with 59.25 hours of vacation available and so far this year has accrued 9.23 hours and has taken 64 hours. The resulting balance should be 4.48, but the report displays current balance as -54.77
I appreciate your effort in posting your concern about your employees' vacation and sick leave reports. However, I'm going to let you contact our Support team for this matter, so they can start a screen-sharing session to review your setup and check your payroll transactions.