To clarify: When you create an output and select the "Update a Feature" output type, you select a "Unique Feature Identifier Field". If there is no feature in the target feature class with a value in the unique identifier field that matches the TRACK_ID value from the input geoevent what happens? I thought that the output would simply create a new feature and move on. However it seems like the output instead throws an error. I would appreciate any feedback, since my desired behavior is that the output create new features as necessary.