Good! I’m puzzled because I remember the solution in previous cases being the opposite, i.e., switching from the \\server\share\xxx syntax to the y:\xxx syntax. But I hope this continues to work for you. Such behavior can be affected by the .NET framework, the VideoReDo COM functions, network properties, etc., all of which can vary with time or setup.
If the problem continues the simplest (although not convenient) work-around is just to not mix transferring and processing.
maybe the act of changing it either way is kind of re-registering it correctly in the frame-work. if it stops working again i will try the other way round. or switch it to a local directory.