Hello,
To quote the iGP Manager Community Manager, "If the button does not appear it is not iGP Manager's fault, it means that the advertisers of the platform have nothing to show at that time for your country/region. We can't do anything about it, it's something external and foreign to us."
You may find that ads seem to disappear if the ad provider doesn't have anything to show, and then in the coming days, ads for rewards will return.
Community Manager