I tried everything. I have installed the latest version of Gog Galaxy, the game was updated with the latest patch, I have disabled the Firewall, but my stats are not uploaded to the Metaverse or in the in-game online stats. Also the in-game GoG avatar/image in corrupted.
Make sure your game graphics presets are on "High", "Extreme", or "Crazy". That's the only way you'll get ranked on the leaderboard. Also make sure the "Upload Results to Leaderboard" box is checked on the initial Benchmark screen.
I just tried this with the latest GOG build and confirmed it does work. You can see my "Extreme" result here.
Avatars are a known issue related to a bug in the GOG SDK. Should be fixed soon.
-Adrian