Think Ive cracked the code. Had a look back through my old appoinments.
If your appointment calendar is set at say half hour increments and your appoinment times fall exactly on the start and beginning of the increments, then the time (in brackets) will
not show.
If however an appointment starts or finshes say 10 min before or after the half hour increments, then the times will display on the left of your entries. Try it.