First off- an apology. I didn't make it clear that the problem is not the ground texture, it is the very visible colour of the spline under the track. I apologise for this.
There is an embankment spline under the track which you will note in my original left-hand image (Tane) is a acceptable match to the surrounding ground, whereas in my righthand image {2019), the embankment is nowhere near the same.
The broader problem is that as part of the update, all the splines, roads and tracks will be modified to get a better match to their surroundings, about 250 items. It will mean that I have to create two sets of updates, one specifically for T:ane and 2017, and another for 2019 which should not be necessary.
Why does 2019 produce this unwanted colour change? This is what I want to solve.
Peter