Im not sure why you would ignore the rest, or how you managed to make it display the times like this? But from 16:16 to 18:47 is not 2h 2min. or from 19:39 to 21:00 its not 1h 1min but 1h 21min.
It's an EL bug. Below 1 hour the "Time Span" columns shows correct value, but when it's 1-2 hours from last uber, it displays as 1h01min.
When it's 2-3 hours it displays 2h02min
3-4 hours displays 3h03min
4-5 hours displays 4h04min
and so on