Hi Isabel,
thanks for reaching out.
I can see that you inserted an Amazon code after the content of each post. This tells me that Advanced Ads works fine. For some reason, Amazon does not fill the ad with content.
You can create an ad with the “Dummy” ad type and add it to the placement to check that Advanced Ads correctly inserts ads.
If that is the case, I would suggest double-checking your Amazon account to see if there is any condition they have before showing ads. You could also try different ad code types to see if others work.
My colleague also wrote an in-depth article about using Amazon: https://wpadvancedads.com/amazon-affiliate-program-wordpress/
It also might give you some guidance.
Let me know how it goes.
Thanks,
Thomas