Service Failure:signal At Danger(out Of Nowhere)

I see this pop up out of nowhere lately on routes where i running just one or two trains with senario planner,yet it shows green signals ahead and i had no saftey systems on at the time?

I did a search for this problem here,but for me it just poped up out of nowhere,if you don't get any kind of warning ahead of time,you won't know to push the b button.

 

Let me guess, East Coastway?

I’ve experienced the same issue. ON TWO DIFFERENT ROUTES.

 

This has happened to me on sand patch grade when I do a coal loading service so I can't use that service at all. I don't get why