I've also asked about this on the Neverwinter Vault, and I've gotten a reply from someone who's identified what script is causing the issue. I'll post it here in case someone here can make use of it:
It's this cutscene script that is the obvious issue as it fires when the door is opened. Doesn't do anything else for me either after the Speakstring line:
GestaltSpeak (22.0, oVar, "Then as my first service to you, Master, let me dispatch of the spy that has been standing behind you.", ANIMATION_NONE, 0.0, 1.0);
NPCs do not go hostile, and the following Speakstring line never follows after the one above. Whatever function is failing after that above line, is also keeping one stuck in the cutscene forever.
#include "in_g_cutscene"
void VarAppear(object oVar);
void main()
{
object oPC = GetFirstPC();
object oNecE = GetObjectByTag("neccut0");
object oNec1 = GetObjectByTag("neccut1");
object oNec2 = GetObjectByTag("neccut2");
object oVar = GetObjectByTag("VarluelofIrasitania");
GestaltStartCutscene(oPC, "tom_varluelcut");
GestaltCameraFade (0.1, oPC, FADE_IN, FADE_SPEED_MEDIUM, 0.5, 0);
GestaltActionAnimate(0.1, oNec1, ANIMATION_LOOPING_MEDITATE, 45.0, 1.0);
GestaltActionAnimate(0.1, oNec2, ANIMATION_LOOPING_MEDITATE, 45.0, 1.0);
GestaltActionAnimate(0.1, oNecE, ANIMATION_LOOPING_MEDITATE, 14.0, 1.0);
GestaltInvisibility (0.0, oVar, 0.0, "");
GestaltSpeak (2.0, oNecE, "...Varluel of Irasitania, I call you forth! Abandon this Rest that you have endured for so long, and walk amongst the living once again!", ANIMATION_NONE, 6.0, 1.0);
GestaltSpeak (8.5, oNecE, "You can not resist this summons, Nya'ri Varluel! Come Forth and be Bound! COME FORTH!", ANIMATION_NONE, 4.0, 1.0);
DelayCommand (11.5, VarAppear(oVar));
DelayCommand (12.0, GestaltClearFX(oVar));
GestaltActionAnimate(13.0, oNecE, ANIMATION_FIREFORGET_BOW, 0.0, 1.0);
GestaltSpeak (13.0, oNecE, "Welcome, great Nya'ri Varluel of Irasitania.", ANIMATION_NONE, 1.0, 1.0);
GestaltSpeak (15.0, oVar, "Where am I? Who are you?", FORCEFUL, 2.0, 1.0);
GestaltSpeak (18.0, oNecE, "You are on the Isle of the Last Rest, and I am your Master, Nya'ri.", LAUGHING, 3.0, 1.0);
GestaltSpeak (22.0, oVar, "Then as my first service to you, Master, let me dispatch of the spy that has been standing behind you.", ANIMATION_NONE, 0.0, 1.0);
GestaltActionFace (25.0, oNecE, 0.0, 0, OBJECT_INVALID);
GestaltSpeak (26.0, oNecE, "The great Nya'tar said that you would come. Prepare to be destroyed, feeble Nya'ri!", LAUGHING, 4.0, 1.0);
GestaltStopCutscene (31.0, oPC, "pcendcutv", TRUE, TRUE, TRUE, TRUE, TRUE, FALSE, 0);
DelayCommand (31.1, ChangeToStandardFaction(oNecE, STANDARD_FACTION_HOSTILE));
DelayCommand (31.1, ChangeToStandardFaction(oVar, STANDARD_FACTION_HOSTILE));
DelayCommand (31.1, ChangeToStandardFaction(oNec1, STANDARD_FACTION_HOSTILE));
DelayCommand (31.1, ChangeToStandardFaction(oNec2, STANDARD_FACTION_HOSTILE));
GestaltCameraMove (0.0, 210.0, 18.0, 35.0, 220.0, 16.0, 30.0, 28.0, 30.0, oPC, 0, 0, 0);
}
void VarAppear(object oVar)
{
ApplyEffectToObject(DURATION_TYPE_INSTANT, EffectVisualEffect(VFX_IMP_HARM), oVar, 1.0);
ApplyEffectToObject(DURATION_TYPE_INSTANT, EffectVisualEffect(VFX_FNF_SUMMON_EPIC_UNDEAD), oVar, 1.0);
ApplyEffectToObject(DURATION_TYPE_INSTANT, EffectVisualEffect(VFX_IMP_RAISE_DEAD), oVar, 1.0);
}