A closing parallel gateway activity doesn't have an endTime timestamp written to the act_hi_actinst table, even after the process has finished - see attached database output (bd_h_actinst_tbl.jpg). Other than appearance, I can't see any other untoward effects on the process. Please see attached process diagram for the structure used (process_dia.jpg).

user forum post:
https://groups.google.com/forum/#!topic/camunda-bpm-users/ZHx8i2R3Frs

Test case is to come