So i was doing 25man ToT on my main up to jikun, then created a group and logged out for my level 100 toons to join. Then when i logged on my level 100 toon, joined, switched to 10 man, i found that the instance used was my fresh alt's lockout (0 bosses killed).
I then tried switching to my main and logged out immediately then logged on my alt. The instance entered is now the saved 25 man instance even though my main changed legacy difficulty to 10 man. I tried waiting a while for my alt to be leader then when i entered, it's a fresh 10 man instance again. Why is this the case? Is this intended or bugged. There wasn't such issues in the past. It's frustrating because my 100 alts are fresh and ungeared toons and are unable to do 25man.