Public transport forgets where to go (Cities: Skylines)

I put any route (train, bus), looped, and after a while the icon (crossed out road) appears, and again after a while the route seems to be "repaired".
At the same time, all vehicles drive, but at the moment when the icon appears, some go further along the route, and some disappear.
Plus, when I try to fix it myself, it says that it's impossible to find a way.
And it is not always possible to complete it the first time when creating a new route. The button is not clickable.