You are not able to flip because you asked the mount to flip a full 10 minutes prior to the meridian. The mount decided it was mechanically unable to reach this position from the opposite pier side so it threw an exception. Try flipping closer to or after the meridian instead of before it.
[8/15/2016 11:18:20 PM] [DEBUG] [Telescope Thread] Pier Flip failed when using side of pier: System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.Runtime.InteropServices.COMException: Setting the side of pier to East cannot be done because the current position cannot be reached with the mount on that side of the pier