Reset mask before clearing stencil (#26737)

src/renderers/WebGLRenderer.js

@@ -629,7 +629,12 @@ class WebGLRenderer {
 			}
 
 			if ( depth ) bits |= _gl.DEPTH_BUFFER_BIT;
-			if ( stencil ) bits |= _gl.STENCIL_BUFFER_BIT;
+			if ( stencil ) {
+
+				bits |= _gl.STENCIL_BUFFER_BIT;
+				this.state.buffers.stencil.setMask( 0xffffffff );
+
+			}
 
 			_gl.clear( bits );