Everything work fine unless I copy a large file (50GB) to an external drive attached to the dock.
The monitor will go black about every minute or two. The audio also is lost. It stays black for about 1-3 seconds then returns.
Once the file copy is complete then the screen black out stops and all things return to normal.
The monitor is a Samsung 40" 4K tv connected to an HDMI cable which is attached to the provided HDMI-DP dongle.
The HDD is a Samsung T3. The failure occurs no matter which port it is connected to (USBC or A).