I have this issue (for the second time now) again! Maybe earlier I hade the DumpNode failure, which I solved nicely by deleting a track surface that was too close to another. Now, on the other hand, there is no track surface nor wall surface that appear to be incorrect. Everything worked great on the track until I changed object properties for a few Objects/SObjects... Anyone have a clue? Could it relate to something else than walls/tracks?
EDIT: I have now been able to solve it thanks to Brendon! Many thanks for helping me out! It appears the SColNodeEx::Split failed is NOT only related to walls, but rather to polygons that are too small. In my case it was a pole I had placed out that I accidentally rescaled so it had an infinite thinness. That meant, when RBR was to load the track the polygons of the object were too small and it ended up with the error message. I could locate the object and delete it thankfully, and now it works again! Thought I would share this with you to add to the troubleshooting process! Look for objects that have too small polygons aswell!