I have the same problem and so far I have tried the force update method mentioned above, fresh re-installing the game, deleting the final fantasy folder with boot config in it to force it to make a new one, and getting specific ports SE tech support told me to forward, after all they they told me themselves they don't know what to do about it and that I should come here and ask other players
I am at a loss for what to do from this point and clearly SE will be of no use, I cannot copy the files I'm missing because the only other person I know of that plays is on Ps4.