diff --git a/common/core/web/input-processor/src/text/inputProcessor.ts b/common/core/web/input-processor/src/text/inputProcessor.ts
index 314d1e8c5ef..e2607cfd7dc 100644
--- a/common/core/web/input-processor/src/text/inputProcessor.ts
+++ b/common/core/web/input-processor/src/text/inputProcessor.ts
@@ -78,9 +78,13 @@ namespace com.keyman.text {
       }
 
       // Will handle keystroke-based non-layer change modifier & state keys, mapping them through the physical keyboard's version
-      // of state management.
-      if(!fromOSK && this.keyboardProcessor.doModifierPress(keyEvent, !fromOSK)) {
-        return new RuleBehavior();
+      // of state management.  `doModifierPress` must always run.
+      if(this.keyboardProcessor.doModifierPress(keyEvent, !fromOSK)) {
+        // If run on a desktop platform, we know that modifier & state key presses may not
+        // produce output, so we may make an immediate return safely.
+        if(!fromOSK) {
+          return new RuleBehavior();
+        }
       }
 
       // If suggestions exist AND space is pressed, accept the suggestion and do not process the keystroke.
diff --git a/common/core/web/keyboard-processor/src/keyboards/activeLayout.ts b/common/core/web/keyboard-processor/src/keyboards/activeLayout.ts
index ae8d65cafb1..3f5e804139a 100644
--- a/common/core/web/keyboard-processor/src/keyboards/activeLayout.ts
+++ b/common/core/web/keyboard-processor/src/keyboards/activeLayout.ts
@@ -217,6 +217,20 @@ namespace com.keyman.keyboards {
       // This part depends on the keyboard processor's active state.
       if(keyboardProcessor) {
         keyboardProcessor.setSyntheticEventDefaults(Lkc);
+
+        // If it's a state key modifier, trigger its effects as part of the
+        // keystroke.
+        const bitmap = {
+          'K_CAPS': text.Codes.stateBitmasks.CAPS,
+          'K_NUMLOCK': text.Codes.stateBitmasks.NUM_LOCK,
+          'K_SCROLL': text.Codes.stateBitmasks.SCROLL_LOCK
+        };
+        const bitmask = bitmap[Lkc.kName];
+
+        if(bitmask) {
+          Lkc.Lstates ^= bitmask;
+          Lkc.LmodifierChange = true;
+        }
       }
 
       return Lkc;
@@ -670,4 +684,4 @@ namespace com.keyman.keyboards {
       return aLayout;
     }
   }
-}
\ No newline at end of file
+}
diff --git a/common/core/web/keyboard-processor/src/text/keyboardProcessor.ts b/common/core/web/keyboard-processor/src/text/keyboardProcessor.ts
index 6ee5d2b9bfc..76e66193366 100644
--- a/common/core/web/keyboard-processor/src/text/keyboardProcessor.ts
+++ b/common/core/web/keyboard-processor/src/text/keyboardProcessor.ts
@@ -406,7 +406,7 @@ namespace com.keyman.text {
 
         for(i=0; i < lockNames.length; i++) {
           if(lockStates & Codes.stateBitmasks[lockNames[i]]) {
-            this.stateKeys[lockKeys[i]] = lockStates & Codes.modifierCodes[lockNames[i]];
+            this.stateKeys[lockKeys[i]] = !!(lockStates & Codes.modifierCodes[lockNames[i]]);
           }
         }
       } else if(d) {
@@ -427,10 +427,44 @@ namespace com.keyman.text {
         }
       }
 
+      this.updateStates();
+
+      if(this.activeKeyboard.isMnemonic && this.stateKeys['K_CAPS']) {
+        // Modifier keypresses doesn't trigger mnemonic manipulation of modifier state.
+        // Only an output key does; active use of Caps will also flip the SHIFT flag.
+        if(!e || !KeyboardProcessor.isModifier(e)) {
+          // Mnemonic keystrokes manipulate the SHIFT property based on CAPS state.
+          // We need to unflip them when tracking the OSK layer.
+          keyShiftState ^= Codes.modifierCodes['SHIFT'];
+        }
+      }
+
       this.layerId = this.getLayerId(keyShiftState);
       return true;
     }
 
+    private updateStates(): void {
+      var lockNames  = ['CAPS', 'NUM_LOCK', 'SCROLL_LOCK'];
+      var lockKeys   = ['K_CAPS', 'K_NUMLOCK', 'K_SCROLL'];
+
+      for(let i=0; i < lockKeys.length; i++) {
+        const key = lockKeys[i];
+        const flag = this.stateKeys[key];
+        const onBit = lockNames[i];
+        const offBit = 'NO_' + lockNames[i];
+
+        // Ensures that the current mod-state info properly matches the currently-simulated
+        // state key states.
+        if(flag) {
+          this.modStateFlags |= Codes.modifierCodes[onBit];
+          this.modStateFlags &= ~Codes.modifierCodes[offBit];
+        } else {
+          this.modStateFlags &= ~Codes.modifierCodes[onBit];
+          this.modStateFlags |= Codes.modifierCodes[offBit];
+        }
+      }
+    }
+
     getLayerId(modifier: number): string {
       return keyboards.Layouts.getLayerId(modifier);
     }
diff --git a/web/source/osk/preProcessor.ts b/web/source/osk/preProcessor.ts
index e8174a05cb9..edcbc0ac3a6 100644
--- a/web/source/osk/preProcessor.ts
+++ b/web/source/osk/preProcessor.ts
@@ -9,14 +9,6 @@ namespace com.keyman.osk {
       // First check the virtual key, and process shift, control, alt or function keys
       let Lkc = e.constructKeyEvent(core.keyboardProcessor, dom.Utils.getOutputTarget(Lelem), keyman.util.device.coreSpec);
 
-      // If it's actually a state key modifier, trigger its effects immediately, as KeyboardEvents would do the same.
-      switch(Lkc.kName) {
-        case 'K_CAPS':
-        case 'K_NUMLOCK':
-        case 'K_SCROLL':
-          core.keyboardProcessor.stateKeys[Lkc.kName] = ! core.keyboardProcessor.stateKeys[Lkc.kName];
-      }
-
       // End - mirrors _GetKeyEventProperties
       return Lkc;
     }
diff --git a/web/source/osk/visualKeyboard.ts b/web/source/osk/visualKeyboard.ts
index 03d4e525dd6..26fffd92e61 100644
--- a/web/source/osk/visualKeyboard.ts
+++ b/web/source/osk/visualKeyboard.ts
@@ -602,7 +602,7 @@ namespace com.keyman.osk {
     layers: keyboards.LayoutLayer[];
     private layerId: string = "default";
     readonly isRTL: boolean;
-    layerIndex: number;
+    layerIndex: number = 0; // the index of the default layer
 
     device: Device;
     isStatic: boolean = false;
@@ -1022,6 +1022,12 @@ namespace com.keyman.osk {
     layerChangeHandler: text.SystemStoreMutationHandler = function(this: VisualKeyboard,
                                                                    source: text.MutableSystemStore,
                                                                    newValue: string) {
+      // This handler is also triggered on state-key state changes (K_CAPS) that 
+      // may not actually change the layer.
+      if(this) {
+        this._UpdateVKShiftStyle();
+      }
+
       if(source.value != newValue) {
         this.layerId = newValue;
         let keyman = com.keyman.singleton;