Looks like the quest leaves him set to "ActorType" and you cannot talk to those.
You can convince him to talk again by executing this through console:
Code:
ch = CharacterFromID("Isenbrandt Jurcksen");
LAi_SetWarriorType(ch);
LAi_warrior_DialogEnable(ch, true);
LAi_warrior_SetStay(ch, true);
See here for details on how:
Tutorial - Modding Tips & Tricks | PiratesAhoy!
However, that isn't an actual fix, since this should be included in the storyline quest code itself!
I had a quick look through it, but it seems there is quite a bit of dealings with him and I'm not familiar enough with the story to know where he should be reset.
@Talisman,
@ANSEL,
@jack sparring or anyone else who IS familiar with the Jack Sparrow storyline,
can you give me an overview of everywhere the Skull/Isenbrandt Jurcksen character is used?
And if you look through quests_reaction.c, could you find some appropriate spots to reset him back to normal with the above lines of code?