Title says it all, the tweak "disable battle music" isn't working in undersigil (pre-Curst, not sure about post. Same map?)
WeiDu.log
Spoiler
// Log of Currently Installed WeiDU Mods
// The top of the file is the 'oldest' mod
// ~TP2_File~ #language_number #component_number // [Subcomponent Name -> ] Component Name [ : Version]
~DDRAWFIX/DDRAWFIX.TP2~ #0 #1 // DDrawFix -> Force DirectDraw Emulation and Cursor Artifact Toggle: v1.0
~WIDESCREEN/WIDESCREEN.TP2~ #0 #0 // Widescreen Mod -> for the original Infinity Engine (CHOOSE THIS!): Widescreen Mod v3.02
~SETUP-GHOSTDOG'S-PST-UI.TP2~ #0 #0 // Planescape Torment User Interface: v2.2
~SETUP-PST-FIX.TP2~ #0 #0 // PS:T Ultimate WeiDU Fixpack, by Qwinn: v4.13
~SETUP-PST-FIX.TP2~ #0 #1 // Dialogue Spelling/Grammar Corrections (English Only): v4.13
~SETUP-PST-FIX.TP2~ #0 #4 // Subtitled Cutscenes: v4.13
~SETUP-PST-UB.TP2~ #0 #50 // Expanded Deionarra's Truth Mod: v4.12
~SETUP-PST-UB.TP2~ #0 #1 // Restored Able Ponder-Thought Research: v4.12
~SETUP-PST-UB.TP2~ #0 #2 // Restored More Morte Mortuary Moments: v4.12
~SETUP-PST-UB.TP2~ #0 #4 // Restored Deionarra's Truth Conversations: v4.12
~SETUP-PST-UB.TP2~ #0 #6 // Restored Elyce's Company: v4.12
~SETUP-PST-UB.TP2~ #0 #7 // Restored Curst Citizens: v4.12
~SETUP-PST-UB.TP2~ #0 #8 // Restored Curst Prisoners: v4.12
~SETUP-PST-UB.TP2~ #0 #9 // Restored Carl Parfidor: v4.12
~SETUP-PST-UB.TP2~ #0 #10 // Restored Morte-Ingress's Teeth Banter: v4.12
~SETUP-PST-UB.TP2~ #0 #11 // Restored Alley of Dangerous Angles Thugs: v4.12
~SETUP-PST-UB.TP2~ #0 #12 // Restored Items: v4.12
~SETUP-PST-UB.TP2~ #0 #13 // Restored Party Comments and Banters: v4.12
~SETUP-PST-UB.TP2~ #0 #14 // Restored Mebbeth: v4.12
~SETUP-PST-UB.TP2~ #0 #15 // Restored Lower Ward Encounters: v4.12
~SETUP-PST-UB.TP2~ #0 #16 // Restored Bestiary Entries: v4.12
~SETUP-PST-TWEAK.TP2~ #0 #1 // Banter Accelerator? If so, Choose interval between banters. -> Interparty Banter Every 6 game hours (30 minutes) <Recommended>: v4.12
~SETUP-PST-TWEAK.TP2~ #0 #22 // BG2-Style THAC0 Display: v4.12
~SETUP-PST-TWEAK.TP2~ #0 #7 // Stackable Rings, Charms, Bracelets, Scrolls: v4.12
~SETUP-PST-TWEAK.TP2~ #0 #14 // Explore City Areas: v4.12
~SETUP-PST-TWEAK.TP2~ #0 #10 // Save Nordom! Tweak: v4.12
~SETUP-PST-TWEAK.TP2~ #0 #5 // Maximized HP Per Level for TNO and Party: v4.12
~SETUP-PST-TWEAK.TP2~ #0 #6 // Maximized Friends Spell: v4.12
~SETUP-PST-TWEAK.TP2~ #0 #20 // Early Glabrezus Tweak: v4.12
~SETUP-GHOSTDOG'S-PST-UI.TP2~ #0 #1 // Bigger fonts? If so, choose language and size. -> 20% bigger fonts for English, French, German, Spanish and Italian languages: v2.2
~SETUP-PST-TWEAK.TP2~ #0 #18 // No Battle Music: v4.12
~1PP_HQ_MUSIC_PST/1PP_HQ_MUSIC_PST.TP2~ #0 #0 // 1pp: High quality music for Planescape Torment
// The top of the file is the 'oldest' mod
// ~TP2_File~ #language_number #component_number // [Subcomponent Name -> ] Component Name [ : Version]
~DDRAWFIX/DDRAWFIX.TP2~ #0 #1 // DDrawFix -> Force DirectDraw Emulation and Cursor Artifact Toggle: v1.0
~WIDESCREEN/WIDESCREEN.TP2~ #0 #0 // Widescreen Mod -> for the original Infinity Engine (CHOOSE THIS!): Widescreen Mod v3.02
~SETUP-GHOSTDOG'S-PST-UI.TP2~ #0 #0 // Planescape Torment User Interface: v2.2
~SETUP-PST-FIX.TP2~ #0 #0 // PS:T Ultimate WeiDU Fixpack, by Qwinn: v4.13
~SETUP-PST-FIX.TP2~ #0 #1 // Dialogue Spelling/Grammar Corrections (English Only): v4.13
~SETUP-PST-FIX.TP2~ #0 #4 // Subtitled Cutscenes: v4.13
~SETUP-PST-UB.TP2~ #0 #50 // Expanded Deionarra's Truth Mod: v4.12
~SETUP-PST-UB.TP2~ #0 #1 // Restored Able Ponder-Thought Research: v4.12
~SETUP-PST-UB.TP2~ #0 #2 // Restored More Morte Mortuary Moments: v4.12
~SETUP-PST-UB.TP2~ #0 #4 // Restored Deionarra's Truth Conversations: v4.12
~SETUP-PST-UB.TP2~ #0 #6 // Restored Elyce's Company: v4.12
~SETUP-PST-UB.TP2~ #0 #7 // Restored Curst Citizens: v4.12
~SETUP-PST-UB.TP2~ #0 #8 // Restored Curst Prisoners: v4.12
~SETUP-PST-UB.TP2~ #0 #9 // Restored Carl Parfidor: v4.12
~SETUP-PST-UB.TP2~ #0 #10 // Restored Morte-Ingress's Teeth Banter: v4.12
~SETUP-PST-UB.TP2~ #0 #11 // Restored Alley of Dangerous Angles Thugs: v4.12
~SETUP-PST-UB.TP2~ #0 #12 // Restored Items: v4.12
~SETUP-PST-UB.TP2~ #0 #13 // Restored Party Comments and Banters: v4.12
~SETUP-PST-UB.TP2~ #0 #14 // Restored Mebbeth: v4.12
~SETUP-PST-UB.TP2~ #0 #15 // Restored Lower Ward Encounters: v4.12
~SETUP-PST-UB.TP2~ #0 #16 // Restored Bestiary Entries: v4.12
~SETUP-PST-TWEAK.TP2~ #0 #1 // Banter Accelerator? If so, Choose interval between banters. -> Interparty Banter Every 6 game hours (30 minutes) <Recommended>: v4.12
~SETUP-PST-TWEAK.TP2~ #0 #22 // BG2-Style THAC0 Display: v4.12
~SETUP-PST-TWEAK.TP2~ #0 #7 // Stackable Rings, Charms, Bracelets, Scrolls: v4.12
~SETUP-PST-TWEAK.TP2~ #0 #14 // Explore City Areas: v4.12
~SETUP-PST-TWEAK.TP2~ #0 #10 // Save Nordom! Tweak: v4.12
~SETUP-PST-TWEAK.TP2~ #0 #5 // Maximized HP Per Level for TNO and Party: v4.12
~SETUP-PST-TWEAK.TP2~ #0 #6 // Maximized Friends Spell: v4.12
~SETUP-PST-TWEAK.TP2~ #0 #20 // Early Glabrezus Tweak: v4.12
~SETUP-GHOSTDOG'S-PST-UI.TP2~ #0 #1 // Bigger fonts? If so, choose language and size. -> 20% bigger fonts for English, French, German, Spanish and Italian languages: v2.2
~SETUP-PST-TWEAK.TP2~ #0 #18 // No Battle Music: v4.12
~1PP_HQ_MUSIC_PST/1PP_HQ_MUSIC_PST.TP2~ #0 #0 // 1pp: High quality music for Planescape Torment
Combat music is disabled everywhere else, btw.