Another poor GoG'er here too. Just got 0.13 installed and now seeing the insufficient membership trying to go multiplayer

In the same boat with the GoG version.

Tried all the different avenues I could think of (on OSX). Still can't manage to find a way to patch to 0.13

have you enabled experimental updates?

Yes sir! Still not finding any updates through the game or on GoG (or GoG Galaxy).

The current version of the GoG Factorio is 0.12.35 (GoG-2).

Edit: I've also tried the previous version available on GoG and the game is still not showing any updates ...

Still faithfully refreshing over at GoG hoping the patch will show up today. Any thoughts on the timeline before it goes live over there?