I caught Dark Tapu Koko with a Master Ball at around 10:09 to 10:12 am Gmt+3 time zone (13 september) . It came after 6 or 7 minutes to my pokemon List.
This time I caught Mystic Arceus (Poison) with a Master Ball at 12:37 to 12:45 but it doesnt show up. It said caught but it is nowhere now.