GPIB Write Freezes and does not timeout or produce error

When using the LabVIEW GPIB Example with NI GPIB hardware and the driver installed I can successfully write to the PSU in question when it is on, however when the PSU is off I expect GPIB Write to timeout (it's set to 1000ms) and produce an error which I pass to a simple error handler (OK message).

Instead LabVIEW freezes on GPIB Write and does not appear to return when inspecting with highlight execution. I have to end task through the task manager to recover.