Please check with advertiser, what’s the start of Thank you page link, is https or http. If it starts with https, that means can’t pass conversion to the http, that why there is no conversion in FuseClick. So you need change the pixel starts with https, and that need you open SSL feature.
Please connect with BD of FuseClick, and discuss the SSL related information and supply the SSL certification to AM of FuseClick, let them to set SSL certification in your account and then the conversion pixel will changed to https, and please replace the old one.