Portal Advanced chambers achievement problem

[76561198064832534]

I did all advanced chambers without any cheat and of course I earned ''Vanilla crazy cake'' but I cant get my ''Cupcake'' achievement. Valve should fix this achievement problem.

[FluffyLemonCake!]

I have the exact same problem.

[76561198064832534]

Valve should fix this problem.

[Gutz]

I've finished all the 6 advanced maps, I have the "vanilla cake" and "fruits cake", but the "cupcake (beating 2 advanced maps)" is still missing :/ it doesn't make sense !

[76561198064832534]

did you played any chamber offline?

[BonePit685]

the same problem with "fruits cake" and yes i played offline

[Calmly Frenetic]

https://steamcommunity.com/sharedfiles/filedetails/?id=419856706