How come the END DATE/TIME is missing on some log entries?

This is caused when the app is killed before an event is ended either by switching to another event (RIDER/NORIDER/PERSONAL/STOP.  MyRideTrac can run all the time in the background.  There should be no need to "kill" the app by swiping up.  Nothing bad happens if you do, you just may not get an end date entered into your log.