Hello,
I noticed that VideoOS.Platform.Data.IExporter.StartExport blocks the calling thread for a view seconds. As I call this method from the UI thread, the UI is not responsible during this time. This behavior can also be seen in the ComponentSamples\ExportSample. I tested with XProtect 2016 R3 Corporate, Expert and Professional. Do you have to call this method from a different thread? Is the AVI/MKVExporter thread-safe?