Not sure if OP is using Galaxy but if not unfortunately the offline installers haven't been updated yet and are still stuck at 1b.
Ups, you are totally right, of course, i really forgot that :(
I hope that offline installers will be updated on Monday, so maybe just a few hours more to wait.
Really, you aren't helping yourself by not using Galaxy for your game installs and updates. GOG doesn't force you to run your games through Galaxy if you'd rather not--all you have to do is run the games from their executables, just as you would a manually installed game, and all of your GOG games will run fine, bypassing Galaxy completely. Just send a shortcut of your game's exe to your desktop and you are there--Galaxy won't run at all when you run the game.
With Galaxy, your game dev can update the game direct to his GOG game dev channel, just as he does with Steam--in both cases the dev can update both Steam and GOG at the same time--or, at least on the same day...;) If he doesn't, that's no fault of Gog's. I've had a couple of games on GOG that were updated through Galaxy the same day they were updated through Steam. In other cases, I own games by developers (who will remain nameless because they have fixed the problem) who simply couldn't be bothered to learn how to use the GOG developer channel to update their GOG games--they'd just email GOG 26GB patches (the entire game) and let GOG sort it out! But they never would admit that the problem was theirs and only existed because they couldn't be bothered with learning how to use the dev update channel, just as they learned how to do it on Steam...;) But they eventually learned how to do it and have done it ever since.
Anyway--if you use Galaxy you will get updates the same day the game dev uploads them to his GOG developer channel. If you do not use Galaxy then you will have to wait a few days past the time the developer makes the patches available to GOG as GOG re configures the patch for the manual backup downloads. So use Galaxy to install your games and update them; but run your games from their executables and bypass Galaxy altogether. Works perfectly on 100% of the GOG library. Later, when the manual patches are made available, you can download them to your backup folder even as you play the updated game!
Really, for games that get a lot of patches before they are finished patching, just install and update through Galaxy, run the games from their executables, and then when the *last patch* comes from the developer--then you can download the full game to your backup game folder! I mean, some games keep patching for years after they ship--no sense downloading all those game and patch files to your backup folder before the dev is finished patching, eh?