It says I have 3 quests available even though I've already completed them.

I don't sell things that are unusual or have a name in it. My game has yet to mess up. But some quest items are stuck in my inventory even though I have already completed the quest. Though it's no biggy,

I've completed the Nightmares quest but he won't acknowledge it. All he says is something along the lines of "You're not as dumb as you look." I've also completed 3 misc quests (sell ore, invest in the alchemy store and find the book) and still nothing.

Also, I've already purchased my second plot of land and I've completed building my second house.

I'll try complete the Civil War quest tonight and see what happens...

The tracking and support for the quests have been spotty; they have some processes that run and update them, but not regularly, so it's not often reflected on the website or in the quest.

Even when the quests have not updated to show that I've completed them, I have still received the message from Xbox Live that they were completed when those messages are applicable (each quest/set of quests don't always have messages associated). So despite
them not being surfaced, they do track completion if you've done the requirements on the backend.

Count yourself lucky!

I have every achievement except Mein Leben, couldn't complete it even if I wanted too

The only quest I can physically complete this month is the downloading from the app one. All the others I can't earn the required achievements as I've already done them.

Were quests only available in the States? I've never even seen a mention of them here.