Not getting chest of reward gems
My youngest son does duolingo on my iPad. He has a 124 day streak. For the last three days I sat beside him when he did it. He is right, he is no longer offered a reward chest when he completes his daily goal, or even when he does more than his daily goal.
Is this a new A/B test?
I've had this happen, too. I get the message I've already received the award that day, but I know it has been 24 hrs since last time.
Try either returning to the 'Learn' screen' (triangle of dots icon) or touch the streak flame icon in the upper left.
I gave you some lingots. Maybe you can pass them on to your son? It's not much but maybe it helps him feel better?
I see the same when (re)doing Hungarian. The reward chest appears immediately when I switch to another language. When I start the day with other languages of my list, the chest is offered as soon as I achieve the target