1) You must install the AJA Adobe AE plug-ins because there is no AE (preferences) video preview setting for the Io Express.
2) Again no AE video preview setting. Use AE menu bar -> Window -> AJA preview instead.
But I have problem. AE work unstable if AJA preview is select(8.1.1 drivers) 🙁
New soft – Io Express Version 8.1.2
Improvements and Fixes
• Addressed an issue where YUV output selections erroneously appeared in After Effects>Video Preview (All).
I have not tested.