as I understand from the screenshot it works with default color scheme but not with the custom color scheme.
I guess that problem is with the custom arrows. The map renderer supports only few resolutions of the one-way pattern. I recommend you to use default one-way pattern or use the same resolution as it is in other color schemes.
With the "default color scheme" as with the "custom color scheme" On 4 road types, there is no one-way route setting. The problem comes from here in my opinion.
Sorry if I restart this topic, but all the one way roads are in the Mca files, so it does not affect the route calculation. It's just a missing parameter problem for displaying one-way routes for some type of segment.