Why my Brave Rewards Disappear after Payment Day

I am new to Brave Reward. I tried to use Brave with activating the Reward system last month. I gained some BAT which mentioned which will be paid within few days ago. However, once it pass the date, the BAT didnt send to my wallet. I have a Brave wallet but did not link to Gemini yet as Gemini is still working on my application. There are no BAT sent to my brave wallet.