Fix concurrency crash with autosave and multicam mode

src/core.cpp

@@ -1098,7 +1098,7 @@ bool Core::enableMultiTrack(bool enable)
     }
     bool isMultiTrack = pCore->monitorManager()->isMultiTrack();
     if (isMultiTrack || enable) {
-        pCore->window()->getMainTimeline()->controller()->slotMultitrackView(enable, enable);
+        pCore->window()->getMainTimeline()->controller()->slotMultitrackView(enable, true);
         return true;
     }
     return false;

src/timeline2/view/timelinecontroller.cpp

@@ -4144,6 +4144,10 @@ bool TimelineController::exists(int itemId)
 void TimelineController::slotMultitrackView(bool enable, bool refresh)
 {
     QStringList trackNames = TimelineFunctions::enableMultitrackView(m_model, enable, refresh);
+    if (!refresh) {
+        // This is just a temporary state (disable multitrack view for playlist save, don't change scene
+        return;
+    }
     pCore->monitorManager()->projectMonitor()->slotShowEffectScene(enable ? MonitorSplitTrack : MonitorSceneNone, false, QVariant(trackNames));
     QObject::disconnect( m_connection );
     if (enable) {