It was the downloadable version! Ah no, I didn't save it the first time, I didn't know how to. But I played again, and the same thing happened again...Maybe someone else can enlighten? Anyway, I have saved it this time. But if the browser version is working for you, it should probably be fine, hmm.
Don't worry too much, whatever I was able to play was so substantial - it could be from my side too! You must have tested the downloadable version too?
Also, I hope you and your team will get time to rest now - that must have been one hell of a ride!