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.
Because of some changes in the theme’s infrastructure, the plugin seems to be problematic for the moment and will be updated soon.
In the meantime as an alternative, starting with v2.4.0, you can see Rey’s new updates in the Dashboard eg: https://d.pr/i/VQZQg8 .