Bug/Issue Some Steam Achievements Do Not Unlock

so apparently some of my steam achievements aren't unlocking... i finished the erchius quest AND killed the poptop mother thing, and i didn't get either one of those achievements. i've done it on several characters and still nothing.
there are other achievements that i've done but didn't get the actual achievements... but the weird part is, i managed to unlock HALF of the achievements on steam, including finishing the main quest
i've tried going offline then online again, and steam is always in online mode
please advise?

steam mirror

edit_
- these are the achievements i'm missing_

• The Hopeful
• Not in Front of the Children!
• Ending Prohibition
• Sweet Revenge
• Feathered Friend
• Captain of the Year
• A Helping Hand
• From the Ashes
• Culinary Century
• Cramped Colony
• Alien Archaeologist
• Nox's Apprentice
• A Cheeky Chore
• A Tireless Task
• Not a Llama
• A Motley Crew
• Well Read
• Bug Free
• Destroyer of Worlds

- these are the achievements i know i didn't do_

• Too Heavy to Kick
• Cosmic Curator
• Them Bones
• Mint Condition
• Armour Aficionado (not sure if i didn't do this one)

 

This is also happening to me too, To tell you the whole story we started playing 6 players on a normal server non dedicated. Everything was fine we all had our achievements unlocking, now we switched to dedicated server which I host , everyone is having his achievements unlocked fine expect me. Now just to be clear I am playing with a Casual character but my friend is also playing with a Casual Character and her Achievements are unlocking fine.
Has anyone encountered this problem before ? It's strange because this happened out of the blue and I did not change anything there are No Mods installed, no cheats , nothing Just a simple dedicated server.

Any help would be appreciated Thank you !