Summary:
Such a situation can happen where the Time off Balance report shows 0 days remaining for 'Today' date whereas for the same user and same time off type, the Time Off History report will show the correct balance when date is chosen as 'This Year'.
 
Resolution:
This happens because the Users Start date might be set to a later date then the policies effective date. Since the system has not encountered the effective date of the policy it is not able to start accruing the balance for this time off type. Changing the Start Date of the employee or modifying the start date of the policy to make both start on the same day will take care of this issue.