Rewarded Ads not showing or rarely show up

I published the game, and my rewarded video is not showing up in most cases.
There is a pool of like 3 videos, once these are shown, ads stop to show which is annoying.
Another thing is that it's always the same 3 ads that are being presented.

Any way to solve this? I ticked 2-3 checkboxes in the ads filter menu in unity dashboard, but still this shouldn't limit these ads to only 3 of them...