There could be two scenarios that could be causing the opening balances to be incorrect:
Transition from Core Product - When the conversion of the balances was done, it was miscalculated. The dollar-to-hours value was not calculated based on the corresponding hourly rate for the employee, which could happen if the employee had a rate increase recently and already had an accrued balance.
The E/D Upload Was done Incorrectly - When creating the earnings entries to add the balances to the employees, they were entered incorrectly. Either by entering a dollar amount that was not correct or by entering an incorrect amount of hours. This could happen if the conversion calculations were not done accurately or if there was a typo at the time of submitting the entry.
If you want to correct the balance, you can do this by running a balance adjustment on the regular payroll or using an off-run. You can also run the Journal Entry report for the pay period immediately before the rest date to see the employee's balance before the reset occurred.
The Leave Management feature is currently available on the Premium Subscription or Pro Subscription with the Leave Management Add-On. In addition, Leave Management requires the Payroll Add On.