diff --git a/Input Source Pro/Utilities/InputSource/InputSourceSwitcher.swift b/Input Source Pro/Utilities/InputSource/InputSourceSwitcher.swift
index 13dfca2..b92d87e 100644
--- a/Input Source Pro/Utilities/InputSource/InputSourceSwitcher.swift	
+++ b/Input Source Pro/Utilities/InputSource/InputSourceSwitcher.swift	
@@ -27,6 +27,11 @@ enum InputSourceSwitcher {
     private static let logger = ISPLogger(category: String(describing: InputSourceSwitcher.self))
     private static var pendingWorkItems: [DispatchWorkItem] = []
 
+    /// End time for the synthetic event suppression window.
+    /// ShortcutTriggerManager checks this to ignore flagsChanged events generated
+    /// by synthetic keyboard events during CJKV input source fix.
+    static var syntheticEventEndTime: TimeInterval = 0
+
     static func discoverInputSources() -> [Descriptor] {
         return inputSourceList().map { source in
             Descriptor(
@@ -117,6 +122,10 @@ enum InputSourceSwitcher {
            let nonCJKVSource = resolveNonCJKVSource(),
            canPostShortcuts()
         {
+            // Suppress modifier event processing in ShortcutTriggerManager for the duration
+            // of the CJKV fix sequence (~300ms) to prevent synthetic keyboard events from
+            // corrupting modifier tracking state and blocking subsequent shortcut triggers.
+            syntheticEventEndTime = ProcessInfo.processInfo.systemUptime + 0.35
             logger.debug { "Applying CJKV fix using previous input source shortcut" }
             selectInputSource(tisTarget, reason: "CJKV target")
             selectInputSource(nonCJKVSource, reason: "CJKV bounce")
@@ -187,6 +196,7 @@ enum InputSourceSwitcher {
     }
 
     private static func cancelPendingWorkItems() {
+        syntheticEventEndTime = 0
         guard !pendingWorkItems.isEmpty else { return }
         pendingWorkItems.forEach { $0.cancel() }
         pendingWorkItems.removeAll()
diff --git a/Input Source Pro/Utilities/ShortcutTrigger.swift b/Input Source Pro/Utilities/ShortcutTrigger.swift
index ec87172..f9634f3 100644
--- a/Input Source Pro/Utilities/ShortcutTrigger.swift	
+++ b/Input Source Pro/Utilities/ShortcutTrigger.swift	
@@ -407,6 +407,14 @@ final class ShortcutTriggerManager {
                         return Unmanaged.passUnretained(event)
                     }
 
+                    // Skip synthetic events posted by our own process (e.g., keyboard events
+                    // from InputSourceSwitcher during CJKV fix). Without this filter, those
+                    // events pollute lastKeyDownTimestamps and invalidate active modifier combos.
+                    let eventPID = event.getIntegerValueField(.eventSourceUnixProcessID)
+                    if eventPID == Int64(ProcessInfo.processInfo.processIdentifier) {
+                        return Unmanaged.passUnretained(event)
+                    }
+
                     let manager = Unmanaged<ShortcutTriggerManager>.fromOpaque(refcon)
                         .takeUnretainedValue()
                     manager.handleKeyEvent(type: type, event: event)
@@ -507,7 +515,12 @@ final class ShortcutTriggerManager {
                 return
             }
 
-            triggerCompletedCombos(at: event.timestamp)
+            // During CJKV fix synthetic event window: keep pressedModifiers in sync
+            // but suppress triggers to prevent phantom switches from synthetic Cmd events.
+            let inSyntheticWindow = ProcessInfo.processInfo.systemUptime < InputSourceSwitcher.syntheticEventEndTime
+            if !inSyntheticWindow {
+                triggerCompletedCombos(at: event.timestamp)
+            }
             comboInvalidated.removeAll()
             comboCompleted.removeAll()
             comboPressTimestamps.removeAll()
@@ -515,6 +528,7 @@ final class ShortcutTriggerManager {
     }
 
     private func updateComboState(pressedKeys: Set<SingleModifierKey>, timestamp: TimeInterval) {
+        let inSyntheticWindow = ProcessInfo.processInfo.systemUptime < InputSourceSwitcher.syntheticEventEndTime
         var didInvalidate = false
 
         for combo in currentCombos {
@@ -530,6 +544,13 @@ final class ShortcutTriggerManager {
             }
 
             if !pressedKeys.isSubset(of: combo.keys) {
+                if inSyntheticWindow {
+                    // During CJKV fix: don't invalidate combos for extra modifiers
+                    // caused by synthetic Cmd key events from InputSourceSwitcher.
+                    // The synthetic modifier will be released shortly; normal combo
+                    // tracking resumes once pressedKeys returns to a valid subset.
+                    continue
+                }
                 comboInvalidated.insert(combo)
                 comboCompleted.remove(combo)
                 comboPressTimestamps.removeValue(forKey: combo)
@@ -588,6 +609,11 @@ final class ShortcutTriggerManager {
         excluding keys: Set<SingleModifierKey>
     ) -> Bool {
         let excludedKeyCodes = Set(keys.map(\.keyCode))
+
+        // Evict entries older than the suppress interval to prevent unbounded growth
+        let cutoff = timestamp - otherKeyPressSuppressInterval
+        lastKeyDownTimestamps = lastKeyDownTimestamps.filter { $0.value >= cutoff }
+
         let lastOtherKeyTimestamp = lastKeyDownTimestamps
             .filter { !excludedKeyCodes.contains($0.key) }
             .map(\.value)