A projector, similar to a TV, is in the “very difficult” category.
Switching on NDI could help.
Settings > My Home > Connected Devices > Network listening
What @kevin1 posted elsewhere applies here:
My advice would be to put it on a smartplug. A projector, like a TV, has a challenging power signature and feeding the data back to Sense via the smartplug will help with the device learning and in the long term could enable you to remove the smartplug and retain detection.