Ads (rewards) showing only when Brave browser is closed

Hi,

I have had an issue with Brave ads for several months now. One day, they disappeared from the browser. I tried everything to get them back, following advices from support community.

Ads finally came back a while ago, but only when I unlock my mac after some time of inactivity.
To illustrate, if I unlock my mac 10 times a day (with 20-30minutes periods), I will receive 10 ads. But when I am surfing on Brave, minutes to several hours, I receive none.

My OS is MacOSCatalina and Brave version is 1.10.93. I am located in the Bay Area.

Do you have an idea on how to fix this ?

Thank you for your help!