I figured it out -- dumb mistake on my part. Somehow, on the Alert Tab, the Motion Zones checkbox wasn't checked.

I've been using BI for some time, with one BI cam for main stream and a 2nd BI cam using the substream DTD. This has been working fine with CPAI, where the motion trigger and AI are done on the substream. Now I've updated the setup to use the suggested substream method and using an Nvidia GPU for CP...