as of alpha 8.0.171 if u updated from 8.0.167 all ur trains will be stopped.
this is very easy to fix: just go through all lines and set your trains to 0 then to 1
Edit: they still dont understand junctions
if you click on train signals view, you can see that your intersections might be too near each other. basically, if a train cross the orange section, it blocks all the near orange sections in each direction
1 train was stuck infront of an empty station no intersection anywhere near