I didn't really manage to create a really descriptive title so here it a more detailed description.

I tried using stacked orders to alternate between several line services. However, I have one service that is only used by stacked orders. When I go to the line properties window, I don't have line timings because it doesn't detect the line is being used in a stacked order (so no reference train).

However, maybe because it is a line service, timings are still shown on each stop at the bottom of the window. I haven't tested with a standalone line.