Manu, the ball is brown and very hard to see on all the outdoor courts for the 18:00 and 19:00 times still for me. Does it appear brown on your computer?
Ok, I may have found what is wrong. When I have the "Shadows" setting set to "All+Stadium" or "All+Crowd", it is fine. But when it is set to anything else (as I had been using), the ball turns brown/very dark yellow at anything after 15:00 (but not at the night setting). It's worst at 18:00. Even the "All" setting it results in this. But with "All+Stadium" and "All+Crowd" there is no problem.