Intensity Shuttle Simultaneous I/O

Is it possible to simultaneously use input and output on the Intensity Shuttle? My current setup has composite into the shuttle, sent to a computer via USB3 running Desktop Video and VDMX. I can successfully use either input or output (composite out in this case), but not both at the same time. Is there some limitation on the shuttle itself or could it possibly be from the software I’m running?

Check for your input and output settings of the BMD (video setup) driver software, otherwise your question is not valid here.

My recollection is that these devices are only one way at a time...

You need one of its big brothers to get two-way functionality.

It all depends how you want to use it, what do you want to achieve ?
Keep in mind that the IS is designed as a video capture device.