To be honest, I don’t know which Matter version is installed on the Plug S MTR Gen3. I can’t find any reliable information on this.
As @mluecke already mentioned, acc. to CSA the Shelly Plug S MTR Gen3 is using the Matter specification v1.2:
(Source)
But the info about the Matter version refers to the Shelly firmware v1.2.0-s1 and my plug has a newer firmware v1.2.3 installed.
I can’t find any detailed information about the Matter version on the Shelly support pages, not even on the by @SunBeech mentioned changelog page. When I open the linked page regarding Matter, it shows only something about version 1.0:
(Source)
Another page states this:
(Source)
So it seems that Shelly doesn’t provide detailed information about Matter, or I haven’t been able to find it. Nevertheless, the reason for the missing energy data will most likely be an “old” Matter version. 
