I recently enabled Brave Rewards and Brave Ads. According to what I know, I am supposed to receive ads from Brave. It has been some time now but I have not gotten a single ad. Is there something wrong? 
Brave Ads is not working!
I think I figured out why I don't get any ads from Brave. I am not in a supported region. I hope this is helpful for someone atleast. 
https://community.brave.com/t/faq-why-am-i-not-seeing-brave-ads/62433
It took some time for me to get ads, but after a while (a couple of weeks I think), they appear, as desktop notifications.
And about the regions. My Linux laptop never said I was in an unsupported region, but my desktop Windows machine did.