I'm having a bug were when changing a vanilla TM block into a custom one within the advanced editor will automatically change the blocks texture to a bright red and will also change whatever surface it is to asphalt. This issue has happened with a; Grass CP (8,4,1,5) - Dirt Platform CP (6,4,1,1) - Platform large wallride (5,3,6,1).
The first times this took place were with the Grass CP and the Asphalt Wallride on out of stadium builds but unfortunately, I do not have the saved files or information on how I got this bug. With the Dirt CP it was an in-stadium Vanilla build and I do have screen shots of the blocks, my graphics settings and also a saved file with the map having a bugged block. Computing the shadows on any setting did not fix at all, as well as a full games restart.