Использование проекции помогло решить эту проблему
https://api.linkedin.com/v2/ugcPosts?q=authors&authors[0]=urn:li:organization:XXXXX&count=100&projection=(paging,elements*(name,localizedName,vanityName,created(actor~(localizedFirstName, localizedLastName)),lastModified(actor~(localizedFirstName, localizedLastName)),specificContent(com.linkedin.ugc.ShareContent(shareMediaCategory,shareCommentary,media(*(media~:playableStreams,originalUrl,description,title))))))