If you’re using Rey theme on a WordPress multisite instance, but don’t enable Rey theme on the main site, you won’t be notified on new Rey theme updates (or its plugins updates).
This is a common problem because the code that is used for pushing update notifications is not loaded on the main site – thus in the network.
To fix this problem i developed a plugin called Rey Module – Multisite Updates and you can download and install from https://github.com/hogash/rey-module-multisite-updates/archive/master.zip .
Simply install it on the Multisite Network Admin > Plugins and activate it. The theme updates should be shown in Dashboard > Updates section.