On windows PC, Brave ad notifications stopped appearing, and sponsored images would not be carried in estimated earnings. Here’s what I did to fix the problem:
I reinstalled the latest version of Brave over the existing installation – Do NOT uninstall your current Brave installation or you’ll loose your BAT.
Under Reward settings, I disabled Brave Rewards. I closed Brave and restarted my computer.
I then reactivated Brave Rewards, and ads returned as well as proper tallying of estimated earnings accumulation.
Hope this helps!