Eu simplesmente esqueci de atribuir o certificado ao endereço IP estático, como pode ser lido aqui: link
After you created or uploaded new certificate into Plesk and wish to use it for domains you should set it for every IP you need, so domains use it when you access them via HTTPS. It can be done on page Server -> IP Addresses -> "choose IP" by selecting needed Certificate in "SSL Certificate" drop down menu.