No achievement in the multiplayer modus

[tomarte2007]

Hi guys, 

I just started an old multiplayer savegame with my friend to get the new achievements. My friend started as the host
We fed the three big spiders and only he got the achievement, I didn't.
As far as I remember, we both used to get an achievement at the same time. 
Is this a bug, or have they changed the settings and I have to start the game as the host?
Can you also tell me whether this is the case with the other achievements? 

Regards,

Thomas