This problem can occur when using a generator with evenly segments but no default. Each segment added to the array effectively acts as an interpolation step used to calculate the banking, so the more segments, the smoother the interpolation. When using only evenly segments, the interpolations steps are few and far between resulting in a rougher and less accurate result.
To fix it you can use segments in the default input instead of evenly then use padding to create the spacing; rework the style to combine default and evenly segments into a single generator; or alternatively include some non-rendering segments in the default input. This could be simple geometry assigned with an invisible material, or an object with vertices but no faces. Ideally we should be able to use an empty segment but it doesn't currently work with this set up. We are looking into this and hopefully it will be fixed in a future update.
I hope that helps.