Hello
Twinmotion can export media and keep rendering/exporting as long as the hardware can handle other application running at the same time Photoshop and Twinmotion. The viewport is not able to keep rendering, thus I recommend you export those images instead. You may experience crashes if your other applications are trying to consume the rest and more of the hardware needed to render.
You can make a suggestion on the road-map for additional rendering features/workflows:
https://portal.productboard.com/7pu88c9kpmqtzt8hwg6arujh/tabs/4-under-consideration
Kind regards,
Vincent B.