Yes, I tried, it will NOT work as expected when both PC and mobile layout are set to be "Scale", and will only if unchecked, but who knows?
So, Still I think this should be token as bug.
Sorry, No.
Just think about that there are several that kind of frame, and I think it should be always recommended to play less animation timelines at same time and pause timelines ON EXIT VIDEW POINT, otherwise, it will need more CPU usage and memory, and potentially cause browser crash especially for MOBILE mode. please check this page you will find there are three same frame animation:
By the way, I am not sure whether this issue is related to this one bug that was confirmed by @daniel before, but that bug is still there in HYPE 4 :
Thanks