How are you trying to run them?
Do they each have their own power adapter and cord?
Are you using a splitter?
Are you using a long 3rd party cord?
I have several cameras running right next to each other. It can absolutely be done.
I’m guessing chances are that you have a power issue. Each V3 camera needs to receive at least 1Amp of power. If they are splitting an adapter or something, it’s likely one isn’t getting enough power. If you’re using a really long 3rd party cord, it’s likely losing too much power before it gets to the camera. You can compensate for this with a different adapter or other things, but it’s likely something like that that you’re having problems with, at least that’s a common thing people run into that I’ve seen in the past.
If it’s none of those things, can you give more details on your setup and what exactly is not working? Does it not turn on? Does it not setup? Does it not stream? What kind of not working?