Schema reviews will not show up on HOME PAGE of a website from now on (ie root domain). This is the newest policy of Google.
Schema reviews showing up in Google SERP is actually UP TO GOOGLE.
Even if you insert the perfect Schema, Google may simply decide not to show the review stars.
Also, you will have to wait a considerable amount of time because it will take some time to appear in the search results.
Make sure you insert the schema in the sub-pages without any errors and wait for Google to crawl them.