If you stopped receiving Items and Chests from the Battlegrounds, there are three possible reasons:
1. Your inventory was full
If you get an Item or Chest reward and both your permanent and temporary inventories are full, it will disappear with no chance of recovery. We highly recommend keeping an eye on your inventory slots and freeing up space beforehand when you are going to conquer a lot of Battlegrounds.
2. You had already received 100 Items and/or Chests during the last 24 hours
There is actually a daily limit on how many Items and Chests you can get or open. After 100 rewards, you stop receiving them from conquering Battlegrounds until the next day.
3. It was a Stoneheart Battleground
There are no Hero Items and Chest rewards for conquering Stoneheart Battlegrounds.