diff --git a/autotests/integration/maximize_test.cpp b/autotests/integration/maximize_test.cpp
--- a/autotests/integration/maximize_test.cpp
+++ b/autotests/integration/maximize_test.cpp
@@ -31,6 +31,8 @@
 #include <KWayland/Client/surface.h>
 #include <KWayland/Client/server_decoration.h>
 #include <KWayland/Client/xdgdecoration.h>
+#include <KWayland/Client/xdgshell.h>
+#include <KWayland/Client/plasmashell.h>
 
 #include <KWayland/Server/shell_interface.h>
 #include <KWayland/Server/xdgdecoration_interface.h>
@@ -55,6 +57,7 @@
     void testInitiallyMaximized();
     void testBorderlessMaximizedWindow();
     void testBorderlessMaximizedWindowNoClientSideDecoration();
+    void testMaximizePlacementStrategy();
 };
 
 void TestMaximized::initTestCase()
@@ -80,7 +83,8 @@
 void TestMaximized::init()
 {
     QVERIFY(Test::setupWaylandConnection(Test::AdditionalWaylandInterface::Decoration |
-                                         Test::AdditionalWaylandInterface::XdgDecoration));
+                                         Test::AdditionalWaylandInterface::XdgDecoration |
+                                         Test::AdditionalWaylandInterface::PlasmaShell));
 
     screens()->setCurrent(0);
     KWin::Cursor::setPos(QPoint(1280, 512));
@@ -294,5 +298,39 @@
     QCOMPARE(deco->mode(), XdgDecoration::Mode::ServerSide);
 }
 
+void TestMaximized::testMaximizePlacementStrategy()
+{
+    // adjust config
+    auto group = kwinApp()->config()->group("Windows");
+    group.writeEntry("Placement", "Maximizing");
+    group.sync();
+    Workspace::self()->slotReconfigure();
+
+    // add a top panel
+    QScopedPointer<Surface> panelSurface(Test::createSurface());
+    QScopedPointer<QObject> panelShellSurface(Test::createXdgShellStableSurface(panelSurface.data()));
+    QScopedPointer<PlasmaShellSurface> plasmaSurface(Test::waylandPlasmaShell()->createSurface(panelSurface.data()));
+    plasmaSurface->setRole(PlasmaShellSurface::Role::Panel);
+    plasmaSurface->setPosition(QPoint(0, 0));
+    Test::renderAndWaitForShown(panelSurface.data(), QSize(1280, 20), Qt::blue);
+
+    // create a new window - it should be maximised on the first configure and positioned beneath the strut
+    QScopedPointer<Surface> surface(Test::createSurface());
+    auto shellSurface = Test::createXdgShellStableSurface(surface.data(), surface.data(), Test::CreationSetup::CreateOnly);
+    QSignalSpy configSpy(shellSurface, &XdgShellSurface::configureRequested);
+    surface->commit(Surface::CommitFlag::None);
+    QVERIFY(configSpy.wait());
+
+    const auto size = configSpy[0][0].toSize();
+    const auto states = configSpy[0][1].value<KWayland::Client::XdgShellSurface::States>();
+    QVERIFY(states & XdgShellSurface::State::Maximized);
+    shellSurface->ackConfigure(configSpy[0][2].toUInt());
+    QCOMPARE(size, QSize(1280, 1024 - 20));
+
+    auto c = Test::renderAndWaitForShown(surface.data(), size, Qt::red);
+    QVERIFY(c);
+    QCOMPARE(c->geometry(), QRect(0, 20, 1280, 1024 - 20));
+}
+
 WAYLANDTEST_MAIN(TestMaximized)
 #include "maximize_test.moc"
diff --git a/placement.cpp b/placement.cpp
--- a/placement.cpp
+++ b/placement.cpp
@@ -376,6 +376,10 @@
  **/
 void Placement::placeCascaded(AbstractClient* c, QRect& area, Policy nextPlacement)
 {
+    if (!c->size().isValid()) {
+        return;
+    }
+
     /* cascadePlacement by Cristian Tibirna (tibirna@kde.org) (30Jan98)
      */
     // work coords
diff --git a/shell_client.cpp b/shell_client.cpp
--- a/shell_client.cpp
+++ b/shell_client.cpp
@@ -372,7 +372,7 @@
     SurfaceInterface *s = surface();
     disconnect(s, &SurfaceInterface::committed, this, &ShellClient::finishInit);
 
-    if (m_xdgShellPopup) {
+    if (!isInitialPositionSet()) {
         QRect area = workspace()->clientArea(PlacementArea, Screens::self()->current(), desktop());
         placeIn(area);
     }