Oksi still won't chat to two of my characters: "Sorry, we're only looking for the best hunters to help our guild". This means one of the two Dread Isle story arcs can't be completed by those characters.
One common factor between those two characters is that they have low PL counts. One has zero PLs (1st life). The other has 3 PLs. The other is that both were L31 when first trying to talk to Oksi. One is now L32 and Oksi still demurs.
Someone else mentioned that using the teleport without running Hidden God might cause it. One character ran Hidden God first. The other did not. So, that's not the trigger.
The 3 other characters I have that could talk to and complete the story arc all have more PLs and also did a mix of porting first or entering via Hidden God.
Whatever is causing him not to chat to some characters simply needs to be removed. If you're playing the game and clicking on him, he should chat and give you the story arc. There is no valid reason to put any kind of gating trigger on him for the story-arc chat.