I had chronos castle knowledge prior to getting to this step.

After talking to the clorince girl and completing her amity quest I received a quest for tachros. Got his amity to 500. No update. 

Reread the quest in my menu and the label on the top left said Unaccepted: befriending tachros as the quest name.

Must have been too long to show on the right. It allows navigation to igor. 

It will not let me forfeit, says cannot find quest data. Switched servers, still eating up a slot.

It should auto update with my knowledge or have a requirement to get 151 amity assuming this is why I cant quit it or re get it. Igor doesn't offer it with it in limbo in my window.

NA, different calpheon servers.

Server reset let this pop up. Done now.

Not sure what issue was.

I had the exact same experience- Got befriend Tachros quest  after already having the amity and already finished the cron castle stuff. Following an update I could "accept" the quest by Igor Bartoli even though it was already present in my quest log (confused how thats possible but it happened), and when I accepted it while already having it, it completed instantly.

Still having a problem with this, dumb you can't forfeit it . It's just sitting there taking up space for me, tried talking to him and Igor and nothing changes.