It`s fun to collect Achievements until it`s not.

I wonder if it will be brought back to my account...
Collected 260+ legendary achievements within Hidden Cats games, and now it has disappeared!
It wasn`t a bug, I just did it first on GOG.
Additionally, five of the games do not trigger Achievements when done.

So it is more like bug hunting. : )

Two tickets were sent. Hopping for a good solution.

Uninstalling Galaxy. Achievements are the only reason for me to use this program. Too many games do not work. Disappearing hard work gained legendary achievements are extremely sad future. No more Galaxy until solved.

Edit:
Breath in.... Breath out.... Breath in...and out... XD ok I'm better now. Coming back to good old life : ) Good Luck! ^

Edit2:

After three months consideration, I came back to achievements hunting with Galaxy : )

GOG Galaxy Legendary achievements appear to be dynamic.

That is to say, a Legendary achievement is evidently one earned by less than 0.5% of total players. As time goes on, naturally, more people get said achievement and it stops being Legendary. If you play a game early enough most of achievements earned would be Legendary, but unless some later patch breaks an achievement making earning it impossible most of those Legendary achievements will degrade in rarity to more appropriate a level.

Also some hiccups happen to occur when you play a game that you didn't get on GOG, allegedly, but the real bad issue with such an integration is that they count achievements earned on other platforms that for some stupid reason weren't implemented in Galaxy as Legendary when they absolutely shouldn't be such, and it massively screws statistics up for everyone, rendering it worse than pointless, when some Steam trash can net you hundreds of Legendaries just by being a game that isn't or doesn't have achievements on GOG.

I reckon the only good way to fix this would be to stop tallying achievements not earned in GOG games when estimating achievement rarity and the amount of Legendaries earned altogether, and maybe loosen the Legendary threshold to 0.7% - 1.0% or thereabouts to make it fair to GOG users.