I just popped a few coffers on 2 different characters and I saw the cubit counter go up then immediately reset to what it had been before.
Likewise collecting coffers in sanctum seems to reset if you never enter world.
Not sure if I lost anything because of this? I wasnt paying close enough attention to other than to see the numbers go straight back down…
I will try to level up someone fast and see if I can recreate it and capture it on video.