UI: Fix changing quick transition to/from fade to black

UI/window-basic-main-transitions.cpp

@@ -1468,6 +1468,7 @@ void OBSBasic::QuickTransitionChange()
 								trIdx);
 		if (tr) {
 			qt->source = tr;
+			qt->fadeToBlack = fadeToBlack;
 			ResetQuickTransitionText(qt);
 		}
 	}