Behavior today - happened twice in some 9-10 runs - no reward present (gold, exp, box) and energy lost in process.
First occured on smartphone, later on PC too
Same here, just happened
You may get lucky and have an unclaimed box when you log back on. Maybe not, seems like the droprate is somewhere near 60%
What i have had to do is just reset the app. In addition to lower drop rates, it is buggy. I suppose they want to run everyone off no?
This can be reproduced with high probability - it is happening after PvP to campaign switch - first campaign after some PvP battle often exhibit this bug.