UI: Fix studio mode label not updating

When studio mode is enabled and OBS is first started, the program
scene label would be empty.

UI/window-basic-main.cpp

@@ -2071,6 +2071,7 @@ void OBSBasic::OBSInit()
 	}
 #endif
 
+	UpdatePreviewProgramIndicators();
 	OnFirstLoad();
 
 	activateWindow();