By the way - way back up in the beginning of the thread, I asked for some info, one piece of which was the driver mode in Sonar.
The reason I did that is that while things may work great in 8.5.3 for you, Sonar maintains a different set of stored parameter settings for Preferences for X3, so if for instance you have Driver Mode in X3 set to something different than for 8.5.3, it may be relevant, which is why I asked.
Sooooo, what driver mode is set in X3?