Leveling up and not getting loot boxes

Same here, got on every level up but now for some reason didn't get on level 22 and 24. Worst thing is that the one I got on leveling to 23 I was saving to stack a few and open at once, but when I just now reached level 24 , not only did I not get the loot box, the old one I gone as well...... Up until level 20 I had no problems whatsoever with either (getting them or stacking them)