I think it takes a few minutes after you search for it to show up. I’ve had the same issue, and I usually can brute force it. If that doesn’t work, then you can check the map link and see if they are federated or blocked. Since you are running your own instance you shouldn’t have issues with blocking or being blocked for now. For example I was trying to make my community discoverable from Midwest.social, but when I looked at the map lemmy.ml (my main instance) and Midwest.social, while not blocking each other, do not appear to be federated. At least not yet.