Bug // End Date Not Calculating Correctly

Bug // End Date Not Calculating Correctly

I have discovered a potential bug in the system. When you set a "Start Date" and then select "Enter Duration" and select "hours" then enter "5" for example the end date does not calculate correctly. This only seems to happen if the Start Date is after working hours. For example, I entered a start date of  09/Dec/16 09:00 PM with a duration of 5 hrs the Due Date calculated as  12/Dec/16 11:00 AM. Could you please take a look at this bug. Also, I would like to be able to enter in a date and time by just typing it in. Having to use the date/time module is slow and cumbersome.