I had a similar problem today, where I got to the victory screen and the daily win counter remained at 3 and no gold was given. I could tell there was a weird delay after the victory screen where the system felt like it "froze" and then moved on.

I had a similar problem today. I had a daily quest to cast 30 blue/white spells.

I alternated between a Standard blue/white robots deck and a Timeless five color Slivers deck.

The pop up appeared normally after the game in which I finished the quest ended. (5c Slivers, I won)

I received XP normally, but the 750 gold wasn't credited to my gold total.

Also seen this but had it together with a card win as the result of a daily win and had a network error with a message like saying to try again later. I had to quit and never seen the reward nor the earned card at my next game start.

Exact same thing happened to me. I played historic ranked I believe but historic none the less and during my game I completed the kill 25 of your opponent's creatures quest for 750 gold. Before my match, I had 650 gold and after my match ended and it popped up on my screen that I completed the quest and I had 3 rewards to collect. 1 was the 750 gold from the quest, 1 was an uncommon card called roiling regrowth, but I can't remember the third reward. I tapped the collect button and my gold amount never changed but I still received the card reward.