Platform, device version and operating system:
What you were expecting to happen, and what actually happened:
I expected to fight the teams shown on the event map of the current “Ancient History” world event. Instead, I often had to fight some other team.
The issue is caused by the refresh mechanism in this event. At some point, the map gets repopulated with new fights. This replaces the battle icons while still retaining the original teams. Restarting the game updates the teams to the ones supposed to be in this place.
To illustrate, this my event map right after it got repopulated. The marked Egg Thief battle used to be a Shadow Dragon battle:
Selecting the marked Egg Thief battle shows I’ll be fighting the replaced Shadow Dragon team instead. This isn’t just a visual issue, this team really shows up in battle:
Restarting the game instead and selecting the very same Egg Thief battle updates the state to the correct battle:
How often does this happen? When did it begin happening?
Every repop during this “Ancient History” world event, ever since it started. There may have been very rare occurences of this in past world events.
Steps to make it happen again
See above. See also this bug report for video documentation.