The issue :

The rails are not properly updated by redstone when the redstone powers already activated rails between other activated rails.

As you can see in the picture, the top rails should be activated like the bottom ones.

How to do this :

1 - Place the raiway.

2 - Place the torch which is on the left in the picture.

3 - Place the torch on the right (in the photo) next to the penultimate activated rail (or one even before it).

Why is this happening? :

When placing the second torch, the rail in front of the torch receives an update and updates the rails around it. However, since the rails around it are already powered, they don't send another update to the rails that surround them. As a result, the rails that are not powered don't get powered as they should.