Sum function returning incorrect results

Hello All,

I encountered a very odd situation when trying to sum up a large amount of cells containing the "time" formatting. It gives a very wrong sum - instead of ~31 hours, it returns ~5hours. I've tried everything, to determine if I have the wrong cell formatting (like text) - I don't; calculated subtotals for each day - worked very well, but when summing up the subtotals, the grand total is also wrong.

Any suggestions would be very much appreciated.

Thank you!

Can you provide a sample workbook? Time formatting will include dates even if it is not seen... I have a feeling if you include the date format with the time format, you will see that the day is increased...