Like I said, it's a good concept. It's just a matter of who sees it, and when. It's also why people usually do interest checks first, to find people and make sure there's an audience. I just found this through scrolling RPs, saw that there wasn't any IC chats yet, and asked to join because I liked the concept. If you want more people, they aren't going to try to join an ongoing RP most likely.
If that's the problem, then one solution would be to post an interest check and restart. It lets people know that you have this idea, and that you're actively looking for people. You'll have me still on board regardless, assuming that you aren't tired of me.