Date & Time: 17 April 2020, bug introduced with patch 5.5
Frequency: About 1/4 (It happened to my group 2/8 times since patch 5.5 was released)
World name: Hyperion, but other members in my party are from other worlds in Primal data center
Character name: Yuriko Cassandra
Monster name: Bahamut Prime
Class/Level: 70
Party or solo: Party
Area and coordinates: The Unending Coil of Bahamut (Ultimate)
Steps:
1. Progress through The Unending Coil of Bahamut (Ultimate) until Bahamut Prime casts "Heavensfall Trio"
2. Twintania, Nael Deus Darnus, and Bahamut Prime appear at the side of the arena, and Twintania and Bahamut Prime cast "Twisting Dive" and "Megaflare Dive" as usual Megaflare dive causes Megaflare markers to appear in 8 out of 16 possible positions around the arena.
3. If one of the selected positions is the position directly at the south edge of the arena, it can appear in the air above the arena instead of on the ground. You can stand underneath it to still satisfy the tower but it is very confusing, and hard to judge where to stand.

I attached a few video links below showing this bug.

https://clips.twitch.tv/SpineyHotSna...56qXxWQpFF4T1l
https://clips.twitch.tv/PlumpUninter...X-0QixqlttkeV3
https://clips.twitch.tv/ArbitraryTub...belwXcg2YvCg-P