Just picked up an AJA UTAP (SDI version) and it works flawlessly with vMix. I use it to capture the program feed from a Black Magic Design ATEM. I noticed, however, that if I was using the UTAP in vMix and opened up the AJA Updater utility, the device would get locked out of vMix (error code "in use"). This is likely because the AJA Utility takes priority of the device, which makes total sense. However, the error persists even after closing the utility program. The only solution I could find was to physically unplug and plug the USB cable for the UTAP back in.

I don't expect many of you will likely need/care about this information, but I figured I would share my experience in case anyone had something similar occur. This is not a vMix issue but rather an issue with the AJA Utility so I will try and share that with their support team as well. Cheers!