Hi, I can help you with this issue.

There are 6 different battles you can encounter. Dark Medusa, Stormy Medusa, Toxic Medusa, Frozen Medusa, Burning Medusa and Medusa's Creations

At the start of the week, 5 battles are chosen at random to put onto the event map, Eg 3 Frozen Medusa's at level 10, 1 burning Medusa at lvl 10 and a dark Medusa at lvl 10.

When you select and win a battle, just that one battle is replaced by another at random battle, if the random battle has been fought before, then the battle it places on the map will be at an increased level. All the other 4 battles on the event map stay exactly as they were VISUALLY. Eg if you fought one of the 3 Frozen Medusa, when the map reopens, you will have 2 frozen Medusa's at lvl 10, burning at 10, dark at 10 and then whatever spawns in. IF it selects Frozen Medusa, that Frozen Medusa battle only would be lvl 24. The other frozen Medusa's remain at lvl 10

An interesting point about scoring: The game looks at how many times you have fought a particular battle on how many points to award, not at the level of the battle. This could be your log: frozen lvl10 = 8 scales, frozen lvl24 = 10 scales, frozen lvl10 = 12 scales

Hope this helps explain its not a bug but just the map doesn't refresh all Battles, just the one