Hi Rui,
I spoke all day with SiteGround and performed a lot a tests they concluded that their HHVM installation is not compatible with the theme and Woocommerce, at least for now.
They have a custom installation I guess and you just have a ON/OFF in cPanel switch to activate HHVM on you server so I don’t really have much information, except that for now it doesn’t work!
If others want to try, backup everything first. It caused the site to go offline 3 times and we had to perform a full site + database restore.
Thank you for the support!
Matt